content/browser/browser_main_loop.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/browser_main_loop.h"

#include <stddef.h>

#include <string>
#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/command_line.h"
#include "base/feature_list.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/memory_coordinator_proxy.h"
#include "base/memory/memory_pressure_monitor.h"
#include "base/memory/ptr_util.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/user_metrics.h"
#include "base/pending_task.h"
#include "base/power_monitor/power_monitor.h"
#include "base/power_monitor/power_monitor_device_source.h"
#include "base/process/process_metrics.h"
#include "base/run_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/synchronization/waitable_event.h"
#include "base/system_monitor/system_monitor.h"
#include "base/task_scheduler/initialization_util.h"
#include "base/task_scheduler/post_task.h"
#include "base/task_scheduler/scheduler_worker_pool_params.h"
#include "base/task_scheduler/task_scheduler.h"
#include "base/task_scheduler/task_traits.h"
#include "base/threading/sequenced_worker_pool.h"
#include "base/threading/thread_restrictions.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/time.h"
#include "base/timer/hi_res_timer_manager.h"
#include "base/trace_event/memory_dump_manager.h"
#include "base/trace_event/trace_event.h"
#include "build/build_config.h"
#include "components/discardable_memory/service/discardable_shared_memory_manager.h"
#include "components/tracing/common/process_metrics_memory_dump_provider.h"
#include "components/tracing/common/trace_config_file.h"
#include "components/tracing/common/trace_to_console.h"
#include "components/tracing/common/tracing_switches.h"
#include "content/browser/audio_manager_thread.h"
#include "content/browser/browser_thread_impl.h"
#include "content/browser/dom_storage/dom_storage_area.h"
#include "content/browser/download/download_resource_handler.h"
#include "content/browser/download/save_file_manager.h"
#include "content/browser/gpu/browser_gpu_channel_host_factory.h"
#include "content/browser/gpu/browser_gpu_memory_buffer_manager.h"
#include "content/browser/gpu/compositor_util.h"
#include "content/browser/gpu/gpu_data_manager_impl.h"
#include "content/browser/gpu/gpu_process_host.h"
#include "content/browser/gpu/gpu_process_host_ui_shim.h"
#include "content/browser/gpu/shader_cache_factory.h"
#include "content/browser/histogram_synchronizer.h"
#include "content/browser/loader/resource_dispatcher_host_impl.h"
#include "content/browser/loader_delegate_impl.h"
#include "content/browser/media/media_internals.h"
#include "content/browser/memory/memory_coordinator_impl.h"
#include "content/browser/net/browser_online_state_observer.h"
#include "content/browser/renderer_host/media/media_stream_manager.h"
#include "content/browser/renderer_host/render_process_host_impl.h"
#include "content/browser/service_manager/service_manager_context.h"
#include "content/browser/speech/speech_recognition_manager_impl.h"
#include "content/browser/startup_task_runner.h"
#include "content/browser/utility_process_host_impl.h"
#include "content/browser/webui/content_web_ui_controller_factory.h"
#include "content/browser/webui/url_data_manager.h"
#include "content/common/content_switches_internal.h"
#include "content/common/host_shared_bitmap_manager.h"
#include "content/common/service_manager/service_manager_connection_impl.h"
#include "content/public/browser/browser_main_parts.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/browser/gpu_data_manager_observer.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/tracing_controller.h"
#include "content/public/common/content_client.h"
#include "content/public/common/content_features.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/main_function_params.h"
#include "content/public/common/result_codes.h"
#include "device/battery/battery_status_service.h"
#include "device/gamepad/gamepad_service.h"
#include "device/sensors/device_sensor_service.h"
#include "media/audio/audio_system_impl.h"
#include "media/base/media.h"
#include "media/base/user_input_monitor.h"
#include "media/midi/midi_service.h"
#include "mojo/edk/embedder/embedder.h"
#include "mojo/edk/embedder/scoped_ipc_support.h"
#include "net/base/network_change_notifier.h"
#include "net/socket/client_socket_factory.h"
#include "net/ssl/ssl_config_service.h"
#include "ppapi/features/features.h"
#include "services/service_manager/runner/common/client_util.h"
#include "skia/ext/event_tracer_impl.h"
#include "skia/ext/skia_memory_dump_provider.h"
#include "sql/sql_memory_dump_provider.h"
#include "ui/base/clipboard/clipboard.h"
#include "ui/gfx/switches.h"

#if defined(USE_AURA) || defined(OS_MACOSX)
#include "content/browser/compositor/image_transport_factory.h"
#endif

#if defined(USE_AURA)
#include "content/public/browser/context_factory.h"
#include "ui/aura/env.h"
#endif

#if defined(OS_ANDROID)
#include "base/android/jni_android.h"
#include "components/tracing/common/graphics_memory_dump_provider_android.h"
#include "content/browser/android/browser_startup_controller.h"
#include "content/browser/android/scoped_surface_request_manager.h"
#include "content/browser/android/tracing_controller_android.h"
#include "content/browser/media/android/browser_media_player_manager.h"
#include "content/browser/renderer_host/context_provider_factory_impl_android.h"
#include "content/browser/screen_orientation/screen_orientation_delegate_android.h"
#include "media/base/android/media_client_android.h"
#include "ui/android/screen_android.h"
#include "ui/display/screen.h"
#include "ui/gl/gl_surface.h"
#endif

#if defined(OS_MACOSX)
#include "base/memory/memory_pressure_monitor_mac.h"
#include "content/browser/bootstrap_sandbox_manager_mac.h"
#include "content/browser/cocoa/system_hotkey_helper_mac.h"
#include "content/browser/mach_broker_mac.h"
#include "content/browser/renderer_host/browser_compositor_view_mac.h"
#include "content/browser/theme_helper_mac.h"
#include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
#endif

#if defined(USE_OZONE)
#include "ui/ozone/public/client_native_pixmap_factory.h"
#endif

#if defined(OS_WIN)
#include <windows.h>
#include <commctrl.h>
#include <shellapi.h>

#include "base/memory/memory_pressure_monitor_win.h"
#include "base/win/windows_version.h"
#include "content/browser/screen_orientation/screen_orientation_delegate_win.h"
#include "content/common/sandbox_win.h"
#include "net/base/winsock_init.h"
#include "ui/base/l10n/l10n_util_win.h"
#endif

#if defined(OS_CHROMEOS)
#include "base/memory/memory_pressure_monitor_chromeos.h"
#include "chromeos/chromeos_switches.h"
#endif

#if defined(USE_GLIB)
#include <glib-object.h>
#endif

#if defined(OS_WIN)
#include "media/device_monitors/system_message_window_win.h"
#elif defined(OS_LINUX) && defined(USE_UDEV)
#include "media/device_monitors/device_monitor_udev.h"
#elif defined(OS_MACOSX)
#include "media/device_monitors/device_monitor_mac.h"
#endif

#if defined(OS_POSIX) && !defined(OS_MACOSX)
#include "content/browser/renderer_host/render_sandbox_host_linux.h"
#include "content/browser/zygote_host/zygote_host_impl_linux.h"

#if !defined(OS_ANDROID)
#include "content/public/browser/zygote_handle_linux.h"
#endif  // !defined(OS_ANDROID)
#endif  // defined(OS_POSIX) && !defined(OS_MACOSX)


#if BUILDFLAG(ENABLE_PLUGINS)
#include "content/browser/plugin_service_impl.h"
#endif

#if defined(ENABLE_MOJO_CDM) && BUILDFLAG(ENABLE_PEPPER_CDMS)
#include "content/browser/media/cdm_registry_impl.h"
#endif

#if defined(USE_X11)
#include "gpu/config/gpu_driver_bug_workaround_type.h"
#include "ui/base/x/x11_util_internal.h"  // nogncheck
#include "ui/gfx/x/x11_connection.h"  // nogncheck
#include "ui/gfx/x/x11_types.h"  // nogncheck
#endif

#if defined(USE_NSS_CERTS)
#include "crypto/nss_util.h"
#endif

#if defined(ENABLE_VULKAN)
#include "gpu/vulkan/vulkan_implementation.h"
#endif

// One of the linux specific headers defines this as a macro.
#ifdef DestroyAll
#undef DestroyAll
#endif

namespace content {
namespace {

#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
void SetupSandbox(const base::CommandLine& parsed_command_line) {
  TRACE_EVENT0("startup", "SetupSandbox");
  if (parsed_command_line.HasSwitch(switches::kNoZygote)) {
    CHECK(parsed_command_line.HasSwitch(switches::kNoSandbox))
        << "--no-sandbox should be used together with --no--zygote";
    return;
  }

  // Tickle the sandbox host and zygote host so they fork now.
  RenderSandboxHostLinux::GetInstance()->Init();
  ZygoteHostImpl::GetInstance()->Init(parsed_command_line);
  *GetGenericZygote() = CreateZygote();
  RenderProcessHostImpl::EarlyZygoteLaunch();
}
#endif

#if defined(USE_GLIB)
static void GLibLogHandler(const gchar* log_domain,
                           GLogLevelFlags log_level,
                           const gchar* message,
                           gpointer userdata) {
  if (!log_domain)
    log_domain = "<unknown>";
  if (!message)
    message = "<no message>";

  if (strstr(message, "Unable to retrieve the file info for")) {
    LOG(ERROR) << "GTK File code error: " << message;
  } else if (strstr(message, "Could not find the icon") &&
             strstr(log_domain, "Gtk")) {
    LOG(ERROR) << "GTK icon error: " << message;
  } else if (strstr(message, "Theme file for default has no") ||
             strstr(message, "Theme directory") ||
             strstr(message, "theme pixmap") ||
             strstr(message, "locate theme engine")) {
    LOG(ERROR) << "GTK theme error: " << message;
  } else if (strstr(message, "Unable to create Ubuntu Menu Proxy") &&
             strstr(log_domain, "<unknown>")) {
    LOG(ERROR) << "GTK menu proxy create failed";
  } else if (strstr(message, "Out of memory") &&
             strstr(log_domain, "<unknown>")) {
    LOG(ERROR) << "DBus call timeout or out of memory: "
               << "http://crosbug.com/15496";
  } else if (strstr(message, "Could not connect: Connection refused") &&
             strstr(log_domain, "<unknown>")) {
    LOG(ERROR) << "DConf settings backend could not connect to session bus: "
               << "http://crbug.com/179797";
  } else if (strstr(message, "Attempting to store changes into") ||
             strstr(message, "Attempting to set the permissions of")) {
    LOG(ERROR) << message << " (http://crbug.com/161366)";
  } else if (strstr(message, "drawable is not a native X11 window")) {
    LOG(ERROR) << message << " (http://crbug.com/329991)";
  } else if (strstr(message, "Cannot do system-bus activation with no user")) {
    LOG(ERROR) << message << " (http://crbug.com/431005)";
  } else if (strstr(message, "deprecated")) {
    LOG(ERROR) << message;
  } else {
    LOG(DFATAL) << log_domain << ": " << message;
  }
}

static void SetUpGLibLogHandler() {
  // Register GLib-handled assertions to go through our logging system.
  const char* const kLogDomains[] =
      { nullptr, "Gtk", "Gdk", "GLib", "GLib-GObject" };
  for (size_t i = 0; i < arraysize(kLogDomains); i++) {
    g_log_set_handler(kLogDomains[i],
                      static_cast<GLogLevelFlags>(G_LOG_FLAG_RECURSION |
                                                  G_LOG_FLAG_FATAL |
                                                  G_LOG_LEVEL_ERROR |
                                                  G_LOG_LEVEL_CRITICAL |
                                                  G_LOG_LEVEL_WARNING),
                      GLibLogHandler,
                      NULL);
  }
}
#endif  // defined(USE_GLIB)

void OnStoppedStartupTracing(const base::FilePath& trace_file) {
  VLOG(0) << "Completed startup tracing to " << trace_file.value();
}

// Disable optimizations for this block of functions so the compiler doesn't
// merge them all together. This makes it possible to tell what thread was
// unresponsive by inspecting the callstack.
MSVC_DISABLE_OPTIMIZE()
MSVC_PUSH_DISABLE_WARNING(4748)

NOINLINE void ResetThread_DB(std::unique_ptr<BrowserProcessSubThread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  if (thread) {
    thread.reset();
  } else {
    BrowserThreadImpl::StopRedirectionOfThreadID(BrowserThread::DB);
  }
}

NOINLINE void ResetThread_FILE(
    std::unique_ptr<BrowserProcessSubThread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  if (thread) {
    thread.reset();
  } else {
    BrowserThreadImpl::StopRedirectionOfThreadID(BrowserThread::FILE);
  }
}

NOINLINE void ResetThread_FILE_USER_BLOCKING(
    std::unique_ptr<BrowserProcessSubThread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  if (thread) {
    thread.reset();
  } else {
    BrowserThreadImpl::StopRedirectionOfThreadID(
        BrowserThread::FILE_USER_BLOCKING);
  }
}

NOINLINE void ResetThread_PROCESS_LAUNCHER(
    std::unique_ptr<BrowserProcessSubThread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  if (thread) {
    thread.reset();
  } else {
    BrowserThreadImpl::StopRedirectionOfThreadID(
        BrowserThread::PROCESS_LAUNCHER);
  }
}

NOINLINE void ResetThread_CACHE(
    std::unique_ptr<BrowserProcessSubThread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  if (thread) {
    thread.reset();
  } else {
    BrowserThreadImpl::StopRedirectionOfThreadID(BrowserThread::CACHE);
  }
}

NOINLINE void ResetThread_IO(std::unique_ptr<BrowserProcessSubThread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  thread.reset();
}

NOINLINE void ResetThread_IndexedDb(std::unique_ptr<base::Thread> thread) {
  volatile int inhibit_comdat = __LINE__;
  ALLOW_UNUSED_LOCAL(inhibit_comdat);
  thread.reset();
}

MSVC_POP_WARNING()
MSVC_ENABLE_OPTIMIZE();

#if defined(OS_WIN)
// Creates a memory pressure monitor using automatic thresholds, or those
// specified on the command-line. Ownership is passed to the caller.
std::unique_ptr<base::win::MemoryPressureMonitor>
CreateWinMemoryPressureMonitor(const base::CommandLine& parsed_command_line) {
  std::vector<std::string> thresholds =
      base::SplitString(parsed_command_line.GetSwitchValueASCII(
                            switches::kMemoryPressureThresholdsMb),
                        ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);

  int moderate_threshold_mb = 0;
  int critical_threshold_mb = 0;
  if (thresholds.size() == 2 &&
      base::StringToInt(thresholds[0], &moderate_threshold_mb) &&
      base::StringToInt(thresholds[1], &critical_threshold_mb) &&
      moderate_threshold_mb >= critical_threshold_mb &&
      critical_threshold_mb >= 0) {
    return base::MakeUnique<base::win::MemoryPressureMonitor>(
        moderate_threshold_mb, critical_threshold_mb);
  }

  // In absence of valid switches use the automatic defaults.
  return base::MakeUnique<base::win::MemoryPressureMonitor>();
}
#endif  // defined(OS_WIN)

enum WorkerPoolType : size_t {
  BACKGROUND = 0,
  BACKGROUND_BLOCKING,
  FOREGROUND,
  FOREGROUND_BLOCKING,
  WORKER_POOL_COUNT  // Always last.
};

std::vector<base::SchedulerWorkerPoolParams>
GetDefaultSchedulerWorkerPoolParams() {
  using StandbyThreadPolicy =
      base::SchedulerWorkerPoolParams::StandbyThreadPolicy;
  using ThreadPriority = base::ThreadPriority;
  std::vector<base::SchedulerWorkerPoolParams> params_vector;
#if defined(OS_ANDROID)
  params_vector.emplace_back(
      "Background", ThreadPriority::BACKGROUND, StandbyThreadPolicy::ONE,
       base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0),
       base::TimeDelta::FromSeconds(30));
  params_vector.emplace_back(
      "BackgroundBlocking", ThreadPriority::BACKGROUND,
      StandbyThreadPolicy::ONE,
      base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0),
      base::TimeDelta::FromSeconds(30));
  params_vector.emplace_back(
      "Foreground", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
       base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0),
       base::TimeDelta::FromSeconds(30));
  params_vector.emplace_back(
      "ForegroundBlocking", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0),
      base::TimeDelta::FromSeconds(30));
#else
  params_vector.emplace_back(
      "Background", ThreadPriority::BACKGROUND, StandbyThreadPolicy::ONE,
       base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0),
       base::TimeDelta::FromSeconds(30));
  params_vector.emplace_back(
      "BackgroundBlocking", ThreadPriority::BACKGROUND,
      StandbyThreadPolicy::ONE,
      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0),
      base::TimeDelta::FromSeconds(30));
  params_vector.emplace_back(
      "Foreground", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
       base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0),
       base::TimeDelta::FromSeconds(30));
  // Tasks posted to SequencedWorkerPool or BrowserThreadImpl may be redirected
  // to this pool. Since COM STA is initialized in these environments, it must
  // also be initialized in this pool.
  params_vector.emplace_back(
      "ForegroundBlocking", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
      base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0),
      base::TimeDelta::FromSeconds(30),
      base::SchedulerBackwardCompatibility::INIT_COM_STA);
#endif
  DCHECK_EQ(WORKER_POOL_COUNT, params_vector.size());
  return params_vector;
}

// Returns the worker pool index for |traits| defaulting to FOREGROUND or
// FOREGROUND_BLOCKING on any other priorities based off of worker pools defined
// in GetDefaultSchedulerWorkerPoolParams().
size_t DefaultBrowserWorkerPoolIndexForTraits(const base::TaskTraits& traits) {
  const bool is_background =
      traits.priority() == base::TaskPriority::BACKGROUND;
  if (traits.may_block() || traits.with_base_sync_primitives())
    return is_background ? BACKGROUND_BLOCKING : FOREGROUND_BLOCKING;

  return is_background ? BACKGROUND : FOREGROUND;
}

}  // namespace

#if defined(USE_X11) && !defined(OS_CHROMEOS)
namespace internal {

// Forwards GPUInfo updates to ui::XVisualManager
class GpuDataManagerVisualProxy : public GpuDataManagerObserver {
 public:
  explicit GpuDataManagerVisualProxy(GpuDataManagerImpl* gpu_data_manager)
      : gpu_data_manager_(gpu_data_manager) {
    gpu_data_manager_->AddObserver(this);
  }

  ~GpuDataManagerVisualProxy() override {
    gpu_data_manager_->RemoveObserver(this);
  }

  void OnGpuInfoUpdate() override {
    if (base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kHeadless))
      return;
    gpu::GPUInfo gpu_info = gpu_data_manager_->GetGPUInfo();
    if (!ui::XVisualManager::GetInstance()->OnGPUInfoChanged(
            gpu_info.software_rendering ||
                !gpu_data_manager_->GpuAccessAllowed(nullptr),
            gpu_info.system_visual, gpu_info.rgba_visual)) {
      // The GPU process sent back bad visuals, which should never happen.
      auto* gpu_process_host = GpuProcessHost::Get(
          GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED, false);
      if (gpu_process_host)
        gpu_process_host->ForceShutdown();
    }
  }

 private:
  GpuDataManagerImpl* gpu_data_manager_;

  DISALLOW_COPY_AND_ASSIGN(GpuDataManagerVisualProxy);
};

}  // namespace internal
#endif

// The currently-running BrowserMainLoop.  There can be one or zero.
BrowserMainLoop* g_current_browser_main_loop = NULL;

#if defined(OS_ANDROID)
bool g_browser_main_loop_shutting_down = false;
#endif

// For measuring memory usage after each task. Behind a command line flag.
class BrowserMainLoop::MemoryObserver : public base::MessageLoop::TaskObserver {
 public:
  MemoryObserver() {}
  ~MemoryObserver() override {}

  void WillProcessTask(const base::PendingTask& pending_task) override {}

  void DidProcessTask(const base::PendingTask& pending_task) override {
    std::unique_ptr<base::ProcessMetrics> process_metrics(
        base::ProcessMetrics::CreateCurrentProcessMetrics());
    size_t private_bytes;
    process_metrics->GetMemoryBytes(&private_bytes, NULL);
    LOCAL_HISTOGRAM_MEMORY_KB("Memory.BrowserUsed", private_bytes >> 10);
  }
 private:
  DISALLOW_COPY_AND_ASSIGN(MemoryObserver);
};


// BrowserMainLoop construction / destruction =============================

BrowserMainLoop* BrowserMainLoop::GetInstance() {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  return g_current_browser_main_loop;
}

BrowserMainLoop::BrowserMainLoop(const MainFunctionParams& parameters)
    : parameters_(parameters),
      parsed_command_line_(parameters.command_line),
      result_code_(RESULT_CODE_NORMAL_EXIT),
      created_threads_(false),
      // ContentMainRunner should have enabled tracing of the browser process
      // when kTraceStartup or kTraceConfigFile is in the command line.
      is_tracing_startup_for_duration_(
          parameters.command_line.HasSwitch(switches::kTraceStartup) ||
          (tracing::TraceConfigFile::GetInstance()->IsEnabled() &&
           tracing::TraceConfigFile::GetInstance()->GetStartupDuration() > 0)) {
  DCHECK(!g_current_browser_main_loop);
  g_current_browser_main_loop = this;
}

BrowserMainLoop::~BrowserMainLoop() {
  DCHECK_EQ(this, g_current_browser_main_loop);
  ui::Clipboard::DestroyClipboardForCurrentThread();
  g_current_browser_main_loop = NULL;
}

void BrowserMainLoop::Init() {
  TRACE_EVENT0("startup", "BrowserMainLoop::Init");

  parts_.reset(
      GetContentClient()->browser()->CreateBrowserMainParts(parameters_));
}

// BrowserMainLoop stages ==================================================

void BrowserMainLoop::EarlyInitialization() {
  TRACE_EVENT0("startup", "BrowserMainLoop::EarlyInitialization");

#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
  // No thread should be created before this call, as SetupSandbox()
  // will end-up using fork().
  SetupSandbox(parsed_command_line_);
#endif

#if defined(USE_X11)
  if (UsingInProcessGpu()) {
    if (!gfx::InitializeThreadedX11()) {
      LOG(ERROR) << "Failed to put Xlib into threaded mode.";
    }
  }
#endif

  // GLib's spawning of new processes is buggy, so it's important that at this
  // point GLib does not need to start DBUS. Chrome should always start with
  // DBUS_SESSION_BUS_ADDRESS properly set. See crbug.com/309093.
#if defined(USE_GLIB)
  // g_type_init will be deprecated in 2.36. 2.35 is the development
  // version for 2.36, hence do not call g_type_init starting 2.35.
  // http://developer.gnome.org/gobject/unstable/gobject-Type-Information.html#g-type-init
#if !GLIB_CHECK_VERSION(2, 35, 0)
  // GLib type system initialization. Needed at least for gconf,
  // used in net/proxy/proxy_config_service_linux.cc. Most likely
  // this is superfluous as gtk_init() ought to do this. It's
  // definitely harmless, so retained as a reminder of this
  // requirement for gconf.
  g_type_init();
#endif  // !GLIB_CHECK_VERSION(2, 35, 0)

  SetUpGLibLogHandler();
#endif  // defined(USE_GLIB)

  if (parts_)
    parts_->PreEarlyInitialization();

#if defined(OS_MACOSX) || defined(OS_LINUX)
  // We use quite a few file descriptors for our IPC as well as disk the disk
  // cache,and the default limit on the Mac is low (256), so bump it up.

  // Same for Linux. The default various per distro, but it is 1024 on Fedora.
  // Low soft limits combined with liberal use of file descriptors means power
  // users can easily hit this limit with many open tabs. Bump up the limit to
  // an arbitrarily high number. See https://crbug.com/539567
  base::SetFdLimit(8192);
#endif  // defined(OS_MACOSX) || defined(OS_LINUX)

#if defined(OS_WIN)
  net::EnsureWinsockInit();
#endif

#if defined(USE_NSS_CERTS)
  // We want to be sure to init NSPR on the main thread.
  crypto::EnsureNSPRInit();
#endif

  if (parsed_command_line_.HasSwitch(switches::kRendererProcessLimit)) {
    std::string limit_string = parsed_command_line_.GetSwitchValueASCII(
        switches::kRendererProcessLimit);
    size_t process_limit;
    if (base::StringToSizeT(limit_string, &process_limit)) {
      RenderProcessHost::SetMaxRendererProcessCount(process_limit);
    }
  }

  if (parts_)
    parts_->PostEarlyInitialization();
}

void BrowserMainLoop::PreMainMessageLoopStart() {
  if (parts_) {
    TRACE_EVENT0("startup",
        "BrowserMainLoop::MainMessageLoopStart:PreMainMessageLoopStart");
    parts_->PreMainMessageLoopStart();
  }

#if defined(OS_WIN)
  // If we're running tests (ui_task is non-null), then the ResourceBundle
  // has already been initialized.
  if (!parameters_.ui_task) {
    // Override the configured locale with the user's preferred UI language.
    l10n_util::OverrideLocaleWithUILanguageList();
  }
#endif
}

void BrowserMainLoop::MainMessageLoopStart() {
  // DO NOT add more code here. Use PreMainMessageLoopStart() above or
  // PostMainMessageLoopStart() below.

  TRACE_EVENT0("startup", "BrowserMainLoop::MainMessageLoopStart");

  // Create a MessageLoop if one does not already exist for the current thread.
  if (!base::MessageLoop::current())
    main_message_loop_.reset(new base::MessageLoopForUI);

  InitializeMainThread();
}

void BrowserMainLoop::PostMainMessageLoopStart() {
  {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:SystemMonitor");
    system_monitor_.reset(new base::SystemMonitor);
  }
  {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:PowerMonitor");
    std::unique_ptr<base::PowerMonitorSource> power_monitor_source(
        new base::PowerMonitorDeviceSource());
    power_monitor_.reset(
        new base::PowerMonitor(std::move(power_monitor_source)));
  }
  {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:HighResTimerManager");
    hi_res_timer_manager_.reset(new base::HighResolutionTimerManager);
  }
  {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:NetworkChangeNotifier");
    network_change_notifier_.reset(net::NetworkChangeNotifier::Create());
  }
  {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:MediaFeatures");
    media::InitializeMediaLibrary();
  }
  {
    TRACE_EVENT0("startup",
                 "BrowserMainLoop::Subsystem:ContentWebUIController");
    WebUIControllerFactory::RegisterFactory(
        ContentWebUIControllerFactory::GetInstance());
  }

  {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:OnlineStateObserver");
    online_state_observer_.reset(new BrowserOnlineStateObserver);
  }

  {
    system_stats_monitor_.reset(
        new base::trace_event::TraceEventSystemStatsMonitor(
            base::ThreadTaskRunnerHandle::Get()));
  }

  {
    base::SetRecordActionTaskRunner(
        BrowserThread::GetTaskRunnerForThread(BrowserThread::UI));
  }

#if defined(OS_WIN)
  if (base::win::GetVersion() >= base::win::VERSION_WIN8)
    screen_orientation_delegate_.reset(new ScreenOrientationDelegateWin());
#endif

  // Only use discardable_memory::DiscardableSharedMemoryManager when Chrome is
  // not running in mus+ash.
  if (!service_manager::ServiceManagerIsRemote()) {
    discardable_shared_memory_manager_ =
        base::MakeUnique<discardable_memory::DiscardableSharedMemoryManager>();
    // TODO(boliu): kSingleProcess check is a temporary workaround for
    // in-process Android WebView. crbug.com/503724 tracks proper fix.
    if (!parsed_command_line_.HasSwitch(switches::kSingleProcess)) {
      base::DiscardableMemoryAllocator::SetInstance(
          discardable_shared_memory_manager_.get());
    }
  }

  if (parts_)
    parts_->PostMainMessageLoopStart();

  // Start startup tracing through TracingController's interface. TraceLog has
  // been enabled in content_main_runner where threads are not available. Now We
  // need to start tracing for all other tracing agents, which require threads.
  if (parsed_command_line_.HasSwitch(switches::kTraceStartup)) {
    base::trace_event::TraceConfig trace_config(
        parsed_command_line_.GetSwitchValueASCII(switches::kTraceStartup),
        base::trace_event::RECORD_UNTIL_FULL);
    TracingController::GetInstance()->StartTracing(
        trace_config,
        TracingController::StartTracingDoneCallback());
  } else if (parsed_command_line_.HasSwitch(switches::kTraceToConsole)) {
      TracingController::GetInstance()->StartTracing(
          tracing::GetConfigForTraceToConsole(),
          TracingController::StartTracingDoneCallback());
  } else if (tracing::TraceConfigFile::GetInstance()->IsEnabled()) {
    // This checks kTraceConfigFile switch.
    TracingController::GetInstance()->StartTracing(
        tracing::TraceConfigFile::GetInstance()->GetTraceConfig(),
        TracingController::StartTracingDoneCallback());
  }
  // Start tracing to a file for certain duration if needed. Only do this after
  // starting the main message loop to avoid calling
  // MessagePumpForUI::ScheduleWork() before MessagePumpForUI::Start() as it
  // will crash the browser.
  if (is_tracing_startup_for_duration_) {
    TRACE_EVENT0("startup", "BrowserMainLoop::InitStartupTracingForDuration");
    InitStartupTracingForDuration(parsed_command_line_);
  }

#if defined(OS_ANDROID)
  {
    TRACE_EVENT0("startup",
                 "BrowserMainLoop::Subsystem:BrowserMediaPlayerManager");
    if (UsingInProcessGpu()) {
      gpu::ScopedSurfaceRequestConduit::SetInstance(
          ScopedSurfaceRequestManager::GetInstance());
    }
  }

  if (!parsed_command_line_.HasSwitch(
      switches::kDisableScreenOrientationLock)) {
    TRACE_EVENT0("startup",
                 "BrowserMainLoop::Subsystem:ScreenOrientationProvider");
    screen_orientation_delegate_.reset(
        new ScreenOrientationDelegateAndroid());
  }
#endif

#if defined(OS_MACOSX)
  if (BootstrapSandboxManager::ShouldEnable()) {
    TRACE_EVENT0("startup",
                 "BrowserMainLoop::Subsystem:BootstrapSandbox");
    CHECK(BootstrapSandboxManager::GetInstance());
  }
#endif

#if defined(USE_OZONE)
  client_native_pixmap_factory_ = ui::ClientNativePixmapFactory::Create();
  ui::ClientNativePixmapFactory::SetInstance(
      client_native_pixmap_factory_.get());
#endif

  if (parsed_command_line_.HasSwitch(switches::kMemoryMetrics)) {
    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:MemoryObserver");
    memory_observer_.reset(new MemoryObserver());
    base::MessageLoop::current()->AddTaskObserver(memory_observer_.get());
  }

  if (parsed_command_line_.HasSwitch(
          switches::kEnableAggressiveDOMStorageFlushing)) {
    TRACE_EVENT0("startup",
                 "BrowserMainLoop::Subsystem:EnableAggressiveCommitDelay");
    DOMStorageArea::EnableAggressiveCommitDelay();
  }

  // Enable memory-infra dump providers.
  InitSkiaEventTracer();
  tracing::ProcessMetricsMemoryDumpProvider::RegisterForProcess(
      base::kNullProcessId);
  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
      HostSharedBitmapManager::current(), "HostSharedBitmapManager", nullptr);
  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
      skia::SkiaMemoryDumpProvider::GetInstance(), "Skia", nullptr);
  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
      sql::SqlMemoryDumpProvider::GetInstance(), "Sql", nullptr);
}

int BrowserMainLoop::PreCreateThreads() {
  // SequencedWorkerPool shouldn't be enabled yet. It should be enabled below by
  // either |parts_|->PreCreateThreads() or
  // base::SequencedWorkerPool::EnableForProcess().
  // TODO(fdoray): Uncomment this line.
  // DCHECK(!base::SequencedWorkerPool::IsEnabled());

  if (parts_) {
    TRACE_EVENT0("startup",
        "BrowserMainLoop::CreateThreads:PreCreateThreads");

    result_code_ = parts_->PreCreateThreads();
  }

  // Enable SequencedWorkerPool if |parts_|->PreCreateThreads() hasn't enabled
  // it.
  // TODO(fdoray): Remove this once the SequencedWorkerPool to TaskScheduler
  // redirection experiment concludes https://crbug.com/622400.
  if (!base::SequencedWorkerPool::IsEnabled())
    base::SequencedWorkerPool::EnableForProcess();

  const base::CommandLine* command_line =
      base::CommandLine::ForCurrentProcess();
  // Note that we do not initialize a new FeatureList when calling this for
  // the second time.
  base::FeatureList::InitializeInstance(
      command_line->GetSwitchValueASCII(switches::kEnableFeatures),
      command_line->GetSwitchValueASCII(switches::kDisableFeatures));

  InitializeMemoryManagementComponent();

  if (base::FeatureList::IsEnabled(features::kMemoryCoordinator))
    MemoryCoordinatorImpl::GetInstance()->Start();

#if BUILDFLAG(ENABLE_PLUGINS)
  // Prior to any processing happening on the IO thread, we create the
  // plugin service as it is predominantly used from the IO thread,
  // but must be created on the main thread. The service ctor is
  // inexpensive and does not invoke the io_thread() accessor.
  {
    TRACE_EVENT0("startup", "BrowserMainLoop::CreateThreads:PluginService");
    PluginService::GetInstance()->Init();
  }
#endif

#if defined(ENABLE_MOJO_CDM) && BUILDFLAG(ENABLE_PEPPER_CDMS)
  // Prior to any processing happening on the IO thread, we create the
  // CDM service as it is predominantly used from the IO thread. This must
  // be called on the main thread since it involves file path checks.
  CdmRegistry::GetInstance()->Init();
#endif

#if defined(OS_MACOSX)
  // The WindowResizeHelper allows the UI thread to wait on specific renderer
  // and GPU messages from the IO thread. Initializing it before the IO thread
  // starts ensures the affected IO thread messages always have somewhere to go.
  ui::WindowResizeHelperMac::Get()->Init(base::ThreadTaskRunnerHandle::Get());
#endif

  // 1) Need to initialize in-process GpuDataManager before creating threads.
  // It's unsafe to append the gpu command line switches to the global
  // CommandLine::ForCurrentProcess object after threads are created.
  // 2) Must be after parts_->PreCreateThreads to pick up chrome://flags.
  GpuDataManagerImpl* gpu_data_manager = GpuDataManagerImpl::GetInstance();
  gpu_data_manager->Initialize();

#if defined(USE_X11) && !defined(OS_CHROMEOS)
  gpu_data_manager_visual_proxy_.reset(
      new internal::GpuDataManagerVisualProxy(gpu_data_manager));
#endif

#if !defined(GOOGLE_CHROME_BUILD) || defined(OS_ANDROID)
  // Single-process is an unsupported and not fully tested mode, so
  // don't enable it for official Chrome builds (except on Android).
  if (parsed_command_line_.HasSwitch(switches::kSingleProcess))
    RenderProcessHost::SetRunRendererInProcess(true);
#endif

  return result_code_;
}

void BrowserMainLoop::PreShutdown() {
  parts_->PreShutdown();

  ui::Clipboard::OnPreShutdownForCurrentThread();
}

void BrowserMainLoop::CreateStartupTasks() {
  TRACE_EVENT0("startup", "BrowserMainLoop::CreateStartupTasks");

  // First time through, we really want to create all the tasks
  if (!startup_task_runner_.get()) {
#if defined(OS_ANDROID)
    startup_task_runner_ = base::MakeUnique<StartupTaskRunner>(
        base::Bind(&BrowserStartupComplete),
        base::ThreadTaskRunnerHandle::Get());
#else
    startup_task_runner_ = base::MakeUnique<StartupTaskRunner>(
        base::Callback<void(int)>(), base::ThreadTaskRunnerHandle::Get());
#endif
    StartupTask pre_create_threads =
        base::Bind(&BrowserMainLoop::PreCreateThreads, base::Unretained(this));
    startup_task_runner_->AddTask(pre_create_threads);

    StartupTask create_threads =
        base::Bind(&BrowserMainLoop::CreateThreads, base::Unretained(this));
    startup_task_runner_->AddTask(create_threads);

    StartupTask browser_thread_started = base::Bind(
        &BrowserMainLoop::BrowserThreadsStarted, base::Unretained(this));
    startup_task_runner_->AddTask(browser_thread_started);

    StartupTask pre_main_message_loop_run = base::Bind(
        &BrowserMainLoop::PreMainMessageLoopRun, base::Unretained(this));
    startup_task_runner_->AddTask(pre_main_message_loop_run);

#if defined(OS_ANDROID)
    if (BrowserMayStartAsynchronously()) {
      startup_task_runner_->StartRunningTasksAsync();
    }
#endif
  }
#if defined(OS_ANDROID)
  if (!BrowserMayStartAsynchronously()) {
    // A second request for asynchronous startup can be ignored, so
    // StartupRunningTasksAsync is only called first time through. If, however,
    // this is a request for synchronous startup then it must override any
    // previous call for async startup, so we call RunAllTasksNow()
    // unconditionally.
    startup_task_runner_->RunAllTasksNow();
  }
#else
  startup_task_runner_->RunAllTasksNow();
#endif
}

int BrowserMainLoop::CreateThreads() {
  TRACE_EVENT0("startup,rail", "BrowserMainLoop::CreateThreads");

  std::vector<base::SchedulerWorkerPoolParams> params_vector;
  base::TaskScheduler::WorkerPoolIndexForTraitsCallback
      index_to_traits_callback;
  GetContentClient()->browser()->GetTaskSchedulerInitializationParams(
      &params_vector, &index_to_traits_callback);

  if (params_vector.empty() || index_to_traits_callback.is_null()) {
    params_vector = GetDefaultSchedulerWorkerPoolParams();
    index_to_traits_callback =
        base::Bind(&DefaultBrowserWorkerPoolIndexForTraits);
  }

  base::TaskScheduler::CreateAndSetDefaultTaskScheduler(
      params_vector, index_to_traits_callback);

  GetContentClient()->browser()->PerformExperimentalTaskSchedulerRedirections();

  base::Thread::Options io_message_loop_options;
  io_message_loop_options.message_loop_type = base::MessageLoop::TYPE_IO;
  base::Thread::Options ui_message_loop_options;
  ui_message_loop_options.message_loop_type = base::MessageLoop::TYPE_UI;

  const bool redirect_nonUInonIO_browser_threads =
      GetContentClient()
          ->browser()
          ->RedirectNonUINonIOBrowserThreadsToTaskScheduler();

  // Start threads in the order they occur in the BrowserThread::ID enumeration,
  // except for BrowserThread::UI which is the main thread.
  //
  // Must be size_t so we can increment it.
  for (size_t thread_id = BrowserThread::UI + 1;
       thread_id < BrowserThread::ID_COUNT;
       ++thread_id) {
    // If this thread ID is backed by a real thread, |thread_to_start| will be
    // set to the appropriate BrowserProcessSubThread*. And |options| can be
    // updated away from its default.
    std::unique_ptr<BrowserProcessSubThread>* thread_to_start = nullptr;
    base::Thread::Options options;

    // Otherwise this thread ID will be backed by a SingleThreadTaskRunner using
    // |non_ui_non_io_task_runner_traits| (which can be augmented below).
    // TODO(gab): Existing non-UI/non-IO BrowserThreads allow sync primitives so
    // the initial redirection will as well but they probably don't need to.
    base::TaskTraits non_ui_non_io_task_runner_traits =
        base::TaskTraits().MayBlock().WithBaseSyncPrimitives();

    switch (thread_id) {
      case BrowserThread::DB:
        TRACE_EVENT_BEGIN1("startup",
            "BrowserMainLoop::CreateThreads:start",
            "Thread", "BrowserThread::DB");
        if (redirect_nonUInonIO_browser_threads) {
          non_ui_non_io_task_runner_traits
              .WithPriority(base::TaskPriority::USER_VISIBLE)
              .WithShutdownBehavior(base::TaskShutdownBehavior::BLOCK_SHUTDOWN);
        } else {
          thread_to_start = &db_thread_;
          options.timer_slack = base::TIMER_SLACK_MAXIMUM;
        }
        break;
      case BrowserThread::FILE_USER_BLOCKING:
        TRACE_EVENT_BEGIN1("startup",
            "BrowserMainLoop::CreateThreads:start",
            "Thread", "BrowserThread::FILE_USER_BLOCKING");
        if (redirect_nonUInonIO_browser_threads) {
          non_ui_non_io_task_runner_traits
              .WithPriority(base::TaskPriority::USER_BLOCKING)
              .WithShutdownBehavior(base::TaskShutdownBehavior::BLOCK_SHUTDOWN);
        } else {
          thread_to_start = &file_user_blocking_thread_;
        }
        break;
      case BrowserThread::FILE:
        TRACE_EVENT_BEGIN1("startup",
            "BrowserMainLoop::CreateThreads:start",
            "Thread", "BrowserThread::FILE");

#if defined(OS_WIN)
        // On Windows, the FILE thread needs to have a UI message loop which
        // pumps messages in such a way that Google Update can communicate back
        // to us.
        // TODO(robliao): Need to support COM in TaskScheduler before
        // redirecting the FILE thread on Windows. http://crbug.com/662122
        thread_to_start = &file_thread_;
        options = ui_message_loop_options;
        options.timer_slack = base::TIMER_SLACK_MAXIMUM;
#else
        if (redirect_nonUInonIO_browser_threads) {
          non_ui_non_io_task_runner_traits
              .WithPriority(base::TaskPriority::USER_VISIBLE)
              .WithShutdownBehavior(base::TaskShutdownBehavior::BLOCK_SHUTDOWN);
        } else {
          thread_to_start = &file_thread_;
          options = io_message_loop_options;
          options.timer_slack = base::TIMER_SLACK_MAXIMUM;
        }
#endif
        break;
      case BrowserThread::PROCESS_LAUNCHER:
        TRACE_EVENT_BEGIN1("startup",
            "BrowserMainLoop::CreateThreads:start",
            "Thread", "BrowserThread::PROCESS_LAUNCHER");
        if (redirect_nonUInonIO_browser_threads) {
          non_ui_non_io_task_runner_traits
              .WithPriority(base::TaskPriority::USER_BLOCKING)
              .WithShutdownBehavior(base::TaskShutdownBehavior::BLOCK_SHUTDOWN);
        } else {
          thread_to_start = &process_launcher_thread_;
          options.timer_slack = base::TIMER_SLACK_MAXIMUM;
        }
        break;
      case BrowserThread::CACHE:
        TRACE_EVENT_BEGIN1("startup",
            "BrowserMainLoop::CreateThreads:start",
            "Thread", "BrowserThread::CACHE");
#if defined(OS_WIN)
        // TaskScheduler doesn't support async I/O on Windows as CACHE thread is
        // the only user and this use case is going away in
        // https://codereview.chromium.org/2216583003/.
        // TODO(gavinp): Remove this ifdef (and thus enable redirection of the
        // CACHE thread on Windows) once that CL lands.
        thread_to_start = &cache_thread_;
        options = io_message_loop_options;
        options.timer_slack = base::TIMER_SLACK_MAXIMUM;
#else  // OS_WIN
        if (redirect_nonUInonIO_browser_threads) {
          non_ui_non_io_task_runner_traits
              .WithPriority(base::TaskPriority::USER_BLOCKING)
              .WithShutdownBehavior(base::TaskShutdownBehavior::BLOCK_SHUTDOWN);
        } else {
          thread_to_start = &cache_thread_;
          options.timer_slack = base::TIMER_SLACK_MAXIMUM;
        }
#endif  // OS_WIN
        break;
      case BrowserThread::IO:
        TRACE_EVENT_BEGIN1("startup",
            "BrowserMainLoop::CreateThreads:start",
            "Thread", "BrowserThread::IO");
        thread_to_start = &io_thread_;
        options = io_message_loop_options;
#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
        // Up the priority of the |io_thread_| as some of its IPCs relate to
        // display tasks.
        options.priority = base::ThreadPriority::DISPLAY;
#endif
        break;
      case BrowserThread::UI:        // Falls through.
      case BrowserThread::ID_COUNT:  // Falls through.
        NOTREACHED();
        break;
    }

    BrowserThread::ID id = static_cast<BrowserThread::ID>(thread_id);

    if (thread_to_start) {
      (*thread_to_start).reset(new BrowserProcessSubThread(id));
      if (!(*thread_to_start)->StartWithOptions(options))
        LOG(FATAL) << "Failed to start the browser thread: id == " << id;
    } else {
      scoped_refptr<base::SingleThreadTaskRunner> redirection_task_runner =
          base::CreateSingleThreadTaskRunnerWithTraits(
              non_ui_non_io_task_runner_traits);
      DCHECK(redirection_task_runner);
      BrowserThreadImpl::RedirectThreadIDToTaskRunner(
          id, std::move(redirection_task_runner));
    }

    TRACE_EVENT_END0("startup", "BrowserMainLoop::CreateThreads:start");
  }
  created_threads_ = true;
  return result_code_;
}

int BrowserMainLoop::PreMainMessageLoopRun() {
#if defined(OS_ANDROID)
  // Let screen instance be overridable by parts.
  ui::SetScreenAndroid();
#endif

  if (parts_) {
    TRACE_EVENT0("startup",
        "BrowserMainLoop::CreateThreads:PreMainMessageLoopRun");

    parts_->PreMainMessageLoopRun();
  }

  // If the UI thread blocks, the whole UI is unresponsive.
  // Do not allow disk IO from the UI thread.
  base::ThreadRestrictions::SetIOAllowed(false);
  base::ThreadRestrictions::DisallowWaiting();
  return result_code_;
}

void BrowserMainLoop::RunMainMessageLoopParts() {
  // Don't use the TRACE_EVENT0 macro because the tracing infrastructure doesn't
  // expect synchronous events around the main loop of a thread.
  TRACE_EVENT_ASYNC_BEGIN0("toplevel", "BrowserMain:MESSAGE_LOOP", this);

  bool ran_main_loop = false;
  if (parts_)
    ran_main_loop = parts_->MainMessageLoopRun(&result_code_);

  if (!ran_main_loop)
    MainMessageLoopRun();

  TRACE_EVENT_ASYNC_END0("toplevel", "BrowserMain:MESSAGE_LOOP", this);
}

void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
  if (!created_threads_) {
    // Called early, nothing to do
    return;
  }
  TRACE_EVENT0("shutdown", "BrowserMainLoop::ShutdownThreadsAndCleanUp");

  // Teardown may start in PostMainMessageLoopRun, and during teardown we
  // need to be able to perform IO.
  base::ThreadRestrictions::SetIOAllowed(true);
  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      base::Bind(base::IgnoreResult(&base::ThreadRestrictions::SetIOAllowed),
                 true));

#if defined(OS_ANDROID)
  g_browser_main_loop_shutting_down = true;
#endif

  if (RenderProcessHost::run_renderer_in_process())
    RenderProcessHostImpl::ShutDownInProcessRenderer();

  if (parts_) {
    TRACE_EVENT0("shutdown",
                 "BrowserMainLoop::Subsystem:PostMainMessageLoopRun");
    parts_->PostMainMessageLoopRun();
  }

  system_stats_monitor_.reset();

  // Destroying the GpuProcessHostUIShims on the UI thread posts a task to
  // delete related objects on the GPU thread. This must be done before
  // stopping the GPU thread. The GPU thread will close IPC channels to renderer
  // processes so this has to happen before stopping the IO thread.
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GPUProcessHostShim");
    GpuProcessHostUIShim::DestroyAll();
  }
  // Cancel pending requests and prevent new requests.
  if (resource_dispatcher_host_) {
    TRACE_EVENT0("shutdown",
                 "BrowserMainLoop::Subsystem:ResourceDispatcherHost");
    resource_dispatcher_host_->Shutdown();
  }
  // Request shutdown to clean up allocated resources on the IO thread.
  if (midi_service_) {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:MidiService");
    midi_service_->Shutdown();
  }

  memory_pressure_monitor_.reset();

#if defined(OS_MACOSX)
  BrowserCompositorMac::DisableRecyclingForShutdown();
#endif

#if defined(USE_AURA) || defined(OS_MACOSX)
  {
    TRACE_EVENT0("shutdown",
                 "BrowserMainLoop::Subsystem:ImageTransportFactory");
    ImageTransportFactory::Terminate();
  }
#endif

  // The device monitors are using |system_monitor_| as dependency, so delete
  // them before |system_monitor_| goes away.
  // On Mac and windows, the monitor needs to be destroyed on the same thread
  // as they were created. On Linux, the monitor will be deleted when IO thread
  // goes away.
#if defined(OS_WIN)
  system_message_window_.reset();
#elif defined(OS_MACOSX)
  device_monitor_mac_.reset();
#endif

  if (BrowserGpuChannelHostFactory::instance()) {
    BrowserGpuChannelHostFactory::instance()->CloseChannel();
  }

  // Shutdown the Service Manager and IPC.
  service_manager_context_.reset();
  mojo_ipc_support_.reset();

  // Must be size_t so we can subtract from it.
  for (size_t thread_id = BrowserThread::ID_COUNT - 1;
       thread_id >= (BrowserThread::UI + 1);
       --thread_id) {
    // Find the thread object we want to stop. Looping over all valid
    // BrowserThread IDs and DCHECKing on a missing case in the switch
    // statement helps avoid a mismatch between this code and the
    // BrowserThread::ID enumeration.
    //
    // The destruction order is the reverse order of occurrence in the
    // BrowserThread::ID list. The rationale for the order is as
    // follows (need to be filled in a bit):
    //
    //
    // - The IO thread is the only user of the CACHE thread.
    //
    // - The PROCESS_LAUNCHER thread must be stopped after IO in case
    //   the IO thread posted a task to terminate a process on the
    //   process launcher thread.
    //
    // - (Not sure why DB stops last.)
    switch (thread_id) {
      case BrowserThread::DB: {
        TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:DBThread");
        ResetThread_DB(std::move(db_thread_));
        break;
      }
      case BrowserThread::FILE: {
        TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:FileThread");
        // Clean up state that lives on or uses the FILE thread before it goes
        // away.
        save_file_manager_->Shutdown();
        ResetThread_FILE(std::move(file_thread_));
        break;
      }
      case BrowserThread::FILE_USER_BLOCKING: {
        TRACE_EVENT0("shutdown",
                      "BrowserMainLoop::Subsystem:FileUserBlockingThread");
        ResetThread_FILE_USER_BLOCKING(std::move(file_user_blocking_thread_));
        break;
      }
      case BrowserThread::PROCESS_LAUNCHER: {
        TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:LauncherThread");
        ResetThread_PROCESS_LAUNCHER(std::move(process_launcher_thread_));
        break;
      }
      case BrowserThread::CACHE: {
        TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:CacheThread");
        ResetThread_CACHE(std::move(cache_thread_));
        break;
      }
      case BrowserThread::IO: {
        TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:IOThread");
        ResetThread_IO(std::move(io_thread_));
        break;
      }
      case BrowserThread::UI:
      case BrowserThread::ID_COUNT:
        NOTREACHED();
        break;
    }
  }
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:IndexedDBThread");
    ResetThread_IndexedDb(std::move(indexed_db_thread_));
  }

  // Close the blocking I/O pool after the other threads. Other threads such
  // as the I/O thread may need to schedule work like closing files or flushing
  // data during shutdown, so the blocking pool needs to be available. There
  // may also be slow operations pending that will blcok shutdown, so closing
  // it here (which will block until required operations are complete) gives
  // more head start for those operations to finish.
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:ThreadPool");
    BrowserThreadImpl::ShutdownThreadPool();
  }
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:TaskScheduler");
    base::TaskScheduler::GetInstance()->Shutdown();
  }

  // Must happen after the IO thread is shutdown since this may be accessed from
  // it.
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GPUChannelFactory");
    if (BrowserGpuChannelHostFactory::instance()) {
#if defined(OS_ANDROID)
      // Clean up the references to the factory before terminating it.
      ui::ContextProviderFactory::SetInstance(nullptr);
      ContextProviderFactoryImpl::Terminate();
#endif
      BrowserGpuChannelHostFactory::Terminate();
    }
  }

  // Must happen after the I/O thread is shutdown since this class lives on the
  // I/O thread and isn't threadsafe.
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GamepadService");
    device::GamepadService::GetInstance()->Terminate();
  }
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:SensorService");
    device::DeviceSensorService::GetInstance()->Shutdown();
  }
#if !defined(OS_ANDROID)
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:BatteryStatusService");
    device::BatteryStatusService::GetInstance()->Shutdown();
  }
#endif
  {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:DeleteDataSources");
    URLDataManager::DeleteDataSources();
  }

  if (parts_) {
    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:PostDestroyThreads");
    parts_->PostDestroyThreads();
  }
}

void BrowserMainLoop::StopStartupTracingTimer() {
  startup_trace_timer_.Stop();
}

void BrowserMainLoop::InitializeMainThread() {
  TRACE_EVENT0("startup", "BrowserMainLoop::InitializeMainThread");
  base::PlatformThread::SetName("CrBrowserMain");

  // Register the main thread by instantiating it, but don't call any methods.
  main_thread_.reset(
      new BrowserThreadImpl(BrowserThread::UI, base::MessageLoop::current()));
}

int BrowserMainLoop::BrowserThreadsStarted() {
  TRACE_EVENT0("startup", "BrowserMainLoop::BrowserThreadsStarted");

  // Bring up Mojo IPC and the embedded Service Manager as early as possible.
  // Initializaing mojo requires the IO thread to have been initialized first,
  // so this cannot happen any earlier than now.
  InitializeMojo();

#if defined(USE_AURA)
  if (service_manager::ServiceManagerIsRemote()) {
    base::CommandLine::ForCurrentProcess()->AppendSwitch(
        switches::kIsRunningInMash);
  }
#endif

  indexed_db_thread_.reset(new base::Thread("IndexedDB"));
  indexed_db_thread_->Start();

  HistogramSynchronizer::GetInstance();
#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
  // Up the priority of the UI thread.
  base::PlatformThread::SetCurrentThreadPriority(base::ThreadPriority::DISPLAY);
#endif

#if defined(ENABLE_VULKAN)
  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kEnableVulkan)) {
    gpu::InitializeVulkan();
  }
#endif

  // Initialize the GPU shader cache. This needs to be initialized before
  // BrowserGpuChannelHostFactory below, since that depends on an initialized
  // ShaderCacheFactory.
  InitShaderCacheFactorySingleton(
      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO),
      BrowserThread::GetTaskRunnerForThread(BrowserThread::CACHE));

  bool always_uses_gpu = true;
  bool established_gpu_channel = false;
#if defined(OS_ANDROID)
  // TODO(crbug.com/439322): This should be set to |true|.
  established_gpu_channel = false;
  always_uses_gpu = ShouldStartGpuProcessOnBrowserStartup();
  BrowserGpuChannelHostFactory::Initialize(established_gpu_channel);
  ContextProviderFactoryImpl::Initialize(
      BrowserGpuChannelHostFactory::instance());
  ui::ContextProviderFactory::SetInstance(
      ContextProviderFactoryImpl::GetInstance());
#elif defined(USE_AURA) || defined(OS_MACOSX)
  established_gpu_channel = true;
  if (!GpuDataManagerImpl::GetInstance()->CanUseGpuBrowserCompositor() ||
      parsed_command_line_.HasSwitch(switches::kDisableGpuEarlyInit) ||
      service_manager::ServiceManagerIsRemote()) {
    established_gpu_channel = always_uses_gpu = false;
  }
  gpu::GpuChannelEstablishFactory* factory =
      GetContentClient()->browser()->GetGpuChannelEstablishFactory();
  if (!factory) {
    BrowserGpuChannelHostFactory::Initialize(established_gpu_channel);
    factory = BrowserGpuChannelHostFactory::instance();
  }
  DCHECK(factory);
  ImageTransportFactory::Initialize();
  ImageTransportFactory::GetInstance()->SetGpuChannelEstablishFactory(factory);
#if defined(USE_AURA)
  bool use_mus_in_renderer = !base::CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kNoUseMusInRenderer);
  if (!use_mus_in_renderer || env_->mode() == aura::Env::Mode::LOCAL) {
    env_->set_context_factory(GetContextFactory());
    env_->set_context_factory_private(GetContextFactoryPrivate());
  }
#endif  // defined(USE_AURA)
#endif  // defined(OS_ANDROID)

  // Enable the GpuMemoryBuffer dump provider with IO thread affinity. Note that
  // unregistration happens on the IO thread (See
  // BrowserProcessSubThread::IOThreadPreCleanUp).
  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
      BrowserGpuMemoryBufferManager::current(), "BrowserGpuMemoryBufferManager",
      io_thread_->task_runner());
#if defined(OS_ANDROID)
  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
      tracing::GraphicsMemoryDumpProvider::GetInstance(), "AndroidGraphics",
      nullptr);
#endif

  {
    TRACE_EVENT0("startup", "BrowserThreadsStarted::Subsystem:AudioMan");
    CreateAudioManager();
  }

  {
    TRACE_EVENT0("startup", "BrowserThreadsStarted::Subsystem:MidiService");
    midi_service_.reset(new midi::MidiService);
  }

#if defined(OS_WIN)
  system_message_window_.reset(new media::SystemMessageWindowWin);
#elif defined(OS_LINUX) && defined(USE_UDEV)
  device_monitor_linux_.reset(
      new media::DeviceMonitorLinux(io_thread_->task_runner()));
#elif defined(OS_MACOSX)
  device_monitor_mac_.reset(new media::DeviceMonitorMac());
#endif

  // RDH needs the IO thread to be created
  {
    TRACE_EVENT0("startup",
      "BrowserMainLoop::BrowserThreadsStarted:InitResourceDispatcherHost");
    // TODO(ananta)
    // We register an interceptor on the ResourceDispatcherHostImpl instance to
    // intercept requests to create handlers for download requests. We need to
    // find a better way to achieve this. Ideally we don't want knowledge of
    // downloads in ResourceDispatcherHostImpl.
    resource_dispatcher_host_.reset(new ResourceDispatcherHostImpl(
        base::Bind(&DownloadResourceHandler::Create)));
    GetContentClient()->browser()->ResourceDispatcherHostCreated();

    loader_delegate_.reset(new LoaderDelegateImpl());
    resource_dispatcher_host_->SetLoaderDelegate(loader_delegate_.get());
  }

  // MediaStreamManager needs the IO thread to be created.
  {
    TRACE_EVENT0("startup",
      "BrowserMainLoop::BrowserThreadsStarted:InitMediaStreamManager");
    media_stream_manager_.reset(new MediaStreamManager(audio_manager_.get()));
  }

  {
    TRACE_EVENT0("startup",
      "BrowserMainLoop::BrowserThreadsStarted:InitSpeechRecognition");
    speech_recognition_manager_.reset(new SpeechRecognitionManagerImpl(
        audio_system_.get(), media_stream_manager_.get()));
  }

  {
    TRACE_EVENT0(
        "startup",
        "BrowserMainLoop::BrowserThreadsStarted::InitUserInputMonitor");
    user_input_monitor_ = media::UserInputMonitor::Create(
        io_thread_->task_runner(), main_thread_->task_runner());
  }

  {
    TRACE_EVENT0("startup",
      "BrowserMainLoop::BrowserThreadsStarted::SaveFileManager");
    save_file_manager_ = new SaveFileManager();
  }

  // Alert the clipboard class to which threads are allowed to access the
  // clipboard:
  std::vector<base::PlatformThreadId> allowed_clipboard_threads;
  // The current thread is the UI thread.
  allowed_clipboard_threads.push_back(base::PlatformThread::CurrentId());
#if defined(OS_WIN)
  // On Windows, clipboard is also used on the IO thread.
  allowed_clipboard_threads.push_back(io_thread_->GetThreadId());
#endif
  ui::Clipboard::SetAllowedThreads(allowed_clipboard_threads);

  // When running the GPU thread in-process, avoid optimistically starting it
  // since creating the GPU thread races against creation of the one-and-only
  // ChildProcess instance which is created by the renderer thread.
  if (GpuDataManagerImpl::GetInstance()->GpuAccessAllowed(NULL) &&
      !established_gpu_channel && always_uses_gpu && !UsingInProcessGpu() &&
      !service_manager::ServiceManagerIsRemote()) {
    TRACE_EVENT_INSTANT0("gpu", "Post task to launch GPU process",
                         TRACE_EVENT_SCOPE_THREAD);
    BrowserThread::PostTask(
        BrowserThread::IO, FROM_HERE,
        base::Bind(base::IgnoreResult(&GpuProcessHost::Get),
                   GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED,
                   true /* force_create */));
  }

#if defined(OS_MACOSX)
  ThemeHelperMac::GetInstance();
  SystemHotkeyHelperMac::GetInstance()->DeferredLoadSystemHotkeys();
#endif  // defined(OS_MACOSX)

#if defined(OS_ANDROID)
  media::SetMediaClientAndroid(GetContentClient()->GetMediaClientAndroid());
#endif

  return result_code_;
}

bool BrowserMainLoop::UsingInProcessGpu() const {
  return parsed_command_line_.HasSwitch(switches::kSingleProcess) ||
         parsed_command_line_.HasSwitch(switches::kInProcessGPU);
}

void BrowserMainLoop::InitializeMemoryManagementComponent() {
  // TODO(chrisha): Abstract away this construction mess to a helper function,
  // once MemoryPressureMonitor is made a concrete class.
#if defined(OS_CHROMEOS)
  if (chromeos::switches::MemoryPressureHandlingEnabled()) {
    memory_pressure_monitor_ =
        base::MakeUnique<base::chromeos::MemoryPressureMonitor>(
            chromeos::switches::GetMemoryPressureThresholds());
  }
#elif defined(OS_MACOSX)
  memory_pressure_monitor_ =
    base::MakeUnique<base::mac::MemoryPressureMonitor>();
#elif defined(OS_WIN)
  memory_pressure_monitor_ =
      CreateWinMemoryPressureMonitor(parsed_command_line_);
#endif

  if (base::FeatureList::IsEnabled(features::kMemoryCoordinator)) {
    // Disable MemoryPressureListener when memory coordinator is enabled.
    base::MemoryPressureListener::SetNotificationsSuppressed(true);
    auto* coordinator = MemoryCoordinatorImpl::GetInstance();
    if (memory_pressure_monitor_) {
      memory_pressure_monitor_->SetDispatchCallback(
          base::Bind(&MemoryCoordinatorImpl::RecordMemoryPressure,
                     base::Unretained(coordinator)));
    }
  }
}

bool BrowserMainLoop::InitializeToolkit() {
  TRACE_EVENT0("startup", "BrowserMainLoop::InitializeToolkit");

  // TODO(evan): this function is rather subtle, due to the variety
  // of intersecting ifdefs we have.  To keep it easy to follow, there
  // are no #else branches on any #ifs.
  // TODO(stevenjb): Move platform specific code into platform specific Parts
  // (Need to add InitializeToolkit stage to BrowserParts).
  // See also GTK setup in EarlyInitialization, above, and associated comments.

#if defined(OS_WIN)
  // Init common control sex.
  INITCOMMONCONTROLSEX config;
  config.dwSize = sizeof(config);
  config.dwICC = ICC_WIN95_CLASSES;
  if (!InitCommonControlsEx(&config))
    PLOG(FATAL);
#endif

#if defined(USE_AURA)

#if defined(USE_X11)
  if (!parsed_command_line_.HasSwitch(switches::kHeadless) &&
      !gfx::GetXDisplay()) {
    LOG(ERROR) << "Unable to open X display.";
    return false;
  }
#endif

  // Env creates the compositor. Aura widgets need the compositor to be created
  // before they can be initialized by the browser.
  env_ = aura::Env::CreateInstance(parameters_.env_mode);
#endif  // defined(USE_AURA)

  if (parts_)
    parts_->ToolkitInitialized();

  return true;
}

void BrowserMainLoop::MainMessageLoopRun() {
#if defined(OS_ANDROID)
  // Android's main message loop is the Java message loop.
  NOTREACHED();
#else
  DCHECK(base::MessageLoopForUI::IsCurrent());
  if (parameters_.ui_task) {
    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                  *parameters_.ui_task);
  }

  base::RunLoop run_loop;
  run_loop.Run();
#endif
}

void BrowserMainLoop::InitializeMojo() {
  if (!parsed_command_line_.HasSwitch(switches::kSingleProcess)) {
    // Disallow mojo sync calls in the browser process. Note that we allow sync
    // calls in single-process mode since renderer IPCs are made from a browser
    // thread.
    bool sync_call_allowed = false;
    MojoResult result = mojo::edk::SetProperty(
        MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED, &sync_call_allowed);
    DCHECK_EQ(MOJO_RESULT_OK, result);
  }

  mojo_ipc_support_.reset(new mojo::edk::ScopedIPCSupport(
      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO),
      mojo::edk::ScopedIPCSupport::ShutdownPolicy::FAST));

  service_manager_context_.reset(new ServiceManagerContext);
#if defined(OS_MACOSX)
  mojo::edk::SetMachPortProvider(MachBroker::GetInstance());
#endif  // defined(OS_MACOSX)
  if (parts_) {
    parts_->ServiceManagerConnectionStarted(
        ServiceManagerConnection::GetForProcess());
  }
}

base::FilePath BrowserMainLoop::GetStartupTraceFileName(
    const base::CommandLine& command_line) const {
  base::FilePath trace_file;
  if (command_line.HasSwitch(switches::kTraceStartup)) {
    trace_file = command_line.GetSwitchValuePath(
        switches::kTraceStartupFile);
    // trace_file = "none" means that startup events will show up for the next
    // begin/end tracing (via about:tracing or AutomationProxy::BeginTracing/
    // EndTracing, for example).
    if (trace_file == base::FilePath().AppendASCII("none"))
      return trace_file;

    if (trace_file.empty()) {
#if defined(OS_ANDROID)
      TracingControllerAndroid::GenerateTracingFilePath(&trace_file);
#else
      // Default to saving the startup trace into the current dir.
      trace_file = base::FilePath().AppendASCII("chrometrace.log");
#endif
    }
  } else {
#if defined(OS_ANDROID)
    TracingControllerAndroid::GenerateTracingFilePath(&trace_file);
#else
    trace_file = tracing::TraceConfigFile::GetInstance()->GetResultFile();
#endif
  }

  return trace_file;
}

void BrowserMainLoop::InitStartupTracingForDuration(
    const base::CommandLine& command_line) {
  DCHECK(is_tracing_startup_for_duration_);

  startup_trace_file_ = GetStartupTraceFileName(parsed_command_line_);

  int delay_secs = 5;
  if (command_line.HasSwitch(switches::kTraceStartup)) {
    std::string delay_str = command_line.GetSwitchValueASCII(
        switches::kTraceStartupDuration);
    if (!delay_str.empty() && !base::StringToInt(delay_str, &delay_secs)) {
      DLOG(WARNING) << "Could not parse --" << switches::kTraceStartupDuration
          << "=" << delay_str << " defaulting to 5 (secs)";
      delay_secs = 5;
    }
  } else {
    delay_secs = tracing::TraceConfigFile::GetInstance()->GetStartupDuration();
  }

  startup_trace_timer_.Start(FROM_HERE,
                             base::TimeDelta::FromSeconds(delay_secs),
                             this,
                             &BrowserMainLoop::EndStartupTracing);
}

void BrowserMainLoop::EndStartupTracing() {
  DCHECK(is_tracing_startup_for_duration_);

  is_tracing_startup_for_duration_ = false;
  TracingController::GetInstance()->StopTracing(
      TracingController::CreateFileSink(
          startup_trace_file_,
          base::Bind(OnStoppedStartupTracing, startup_trace_file_)));
}

void BrowserMainLoop::CreateAudioManager() {
  DCHECK(!audio_thread_);
  DCHECK(!audio_manager_);

  audio_manager_ = GetContentClient()->browser()->CreateAudioManager(
      MediaInternals::GetInstance());
  if (!audio_manager_) {
    audio_thread_ = base::MakeUnique<AudioManagerThread>();
    audio_manager_ = media::AudioManager::Create(
        audio_thread_->task_runner(), audio_thread_->worker_task_runner(),
        MediaInternals::GetInstance());
  }
  CHECK(audio_manager_);

  audio_system_ = media::AudioSystemImpl::Create(audio_manager_.get());
  CHECK(audio_system_);
}

}  // namespace content