chrome/browser/extensions/extension_service.h

// 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.

#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_SERVICE_H_
#define CHROME_BROWSER_EXTENSIONS_EXTENSION_SERVICE_H_

#include <list>
#include <map>
#include <set>
#include <string>
#include <vector>

#include "base/compiler_specific.h"
#include "base/files/file_path.h"
#include "base/gtest_prod_util.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/prefs/pref_change_registrar.h"
#include "base/strings/string16.h"
#include "chrome/browser/extensions/blacklist.h"
#include "chrome/browser/extensions/extension_sync_service.h"
#include "chrome/browser/extensions/pending_extension_manager.h"
#include "chrome/common/extensions/extension_constants.h"
#include "content/public/browser/devtools_agent_host.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"
#include "extensions/browser/extension_function_histogram_value.h"
#include "extensions/browser/extension_prefs.h"
#include "extensions/browser/external_provider_interface.h"
#include "extensions/browser/management_policy.h"
#include "extensions/browser/process_manager.h"
#include "extensions/common/extension.h"
#include "extensions/common/extension_set.h"
#include "extensions/common/manifest.h"
#include "extensions/common/manifest_handlers/shared_module_info.h"
#include "extensions/common/one_shot_event.h"

class ExtensionErrorUI;
class GURL;
class Profile;

namespace base {
class CommandLine;
class SequencedTaskRunner;
class Version;
}

namespace extensions {
class BrowserEventRouter;
class ComponentLoader;
class CrxInstaller;
class ExtensionActionStorageManager;
class ExtensionGarbageCollector;
class ExtensionRegistry;
class ExtensionSystem;
class ExtensionToolbarModel;
class ExtensionUpdater;
class PendingExtensionManager;
class RendererStartupHelper;
class UpdateObserver;
}  // namespace extensions

using extensions::ExtensionIdSet;

namespace syncer {
class SyncErrorFactory;
}

// This is an interface class to encapsulate the dependencies that
// various classes have on ExtensionService. This allows easy mocking.
class ExtensionServiceInterface
    : public base::SupportsWeakPtr<ExtensionServiceInterface> {
 public:
  virtual ~ExtensionServiceInterface() {}

  // DEPRECATED: Use ExtensionRegistry::enabled_extensions() instead.
  // ExtensionRegistry also has the disabled, terminated and blacklisted sets.
  virtual const extensions::ExtensionSet* extensions() const = 0;

  virtual extensions::PendingExtensionManager* pending_extension_manager() = 0;

  // Install an update.  Return true if the install can be started.
  // Set out_crx_installer to the installer if one was started.
  virtual bool UpdateExtension(
      const std::string& id,
      const base::FilePath& path,
      bool file_ownership_passed,
      const GURL& download_url,
      extensions::CrxInstaller** out_crx_installer) = 0;
  virtual const extensions::Extension* GetExtensionById(
      const std::string& id,
      bool include_disabled) const = 0;
  virtual const extensions::Extension* GetInstalledExtension(
      const std::string& id) const = 0;

  virtual const extensions::Extension* GetPendingExtensionUpdate(
      const std::string& extension_id) const = 0;
  virtual void FinishDelayedInstallation(const std::string& extension_id) = 0;

  virtual bool IsExtensionEnabled(const std::string& extension_id) const = 0;

  virtual void CheckManagementPolicy() = 0;

  // Safe to call multiple times in a row.
  //
  // TODO(akalin): Remove this method (and others) once we refactor
  // themes sync to not use it directly.
  virtual void CheckForUpdatesSoon() = 0;

  virtual void AddExtension(const extensions::Extension* extension) = 0;
  virtual void AddComponentExtension(
      const extensions::Extension* extension) = 0;

  virtual void UnloadExtension(
      const std::string& extension_id,
      extensions::UnloadedExtensionInfo::Reason reason) = 0;
  virtual void RemoveComponentExtension(const std::string& extension_id) = 0;

  virtual bool is_ready() = 0;

  // Returns task runner for crx installation file I/O operations.
  virtual base::SequencedTaskRunner* GetFileTaskRunner() = 0;
};

// Manages installed and running Chromium extensions. An instance is shared
// between normal and incognito profiles.
class ExtensionService
    : public ExtensionServiceInterface,
      public extensions::ExternalProviderInterface::VisitorInterface,
      public content::NotificationObserver,
      public extensions::Blacklist::Observer {
 public:
  // Returns the Extension for a given url or NULL if the url doesn't belong to
  // an installed extension. This may be a hosted app extent or a
  // chrome-extension:// url.
  const extensions::Extension* GetInstalledExtensionByUrl(
      const GURL& url) const;

  // Returns the Extension of hosted or packaged apps, NULL otherwise.
  const extensions::Extension* GetInstalledApp(const GURL& url) const;

  // Returns whether the URL is from either a hosted or packaged app.
  bool IsInstalledApp(const GURL& url) const;

  // Attempts to uninstall an extension from a given ExtensionService. Returns
  // true iff the target extension exists.
  static bool UninstallExtensionHelper(ExtensionService* extensions_service,
                                       const std::string& extension_id);

  // Constructor stores pointers to |profile| and |extension_prefs| but
  // ownership remains at caller.
  ExtensionService(Profile* profile,
                   const base::CommandLine* command_line,
                   const base::FilePath& install_directory,
                   extensions::ExtensionPrefs* extension_prefs,
                   extensions::Blacklist* blacklist,
                   bool autoupdate_enabled,
                   bool extensions_enabled,
                   extensions::OneShotEvent* ready);

  virtual ~ExtensionService();

  // DEPRECATED: Use ExtensionRegistry::enabled_extensions() instead.
  // ExtensionRegistry also has the disabled, terminated and blacklisted sets.
  virtual const extensions::ExtensionSet* extensions() const OVERRIDE;

  const extensions::ExtensionSet* delayed_installs() const;

  // Gets the object managing the set of pending extensions.
  virtual extensions::PendingExtensionManager*
      pending_extension_manager() OVERRIDE;

  const base::FilePath& install_directory() const { return install_directory_; }

  // Getter and setter for the flag that specifies whether the extension is
  // being reloaded.
  bool IsBeingReloaded(const std::string& extension_id) const;
  void SetBeingReloaded(const std::string& extension_id, bool value);

  // Initialize and start all installed extensions.
  void Init();

  // Called when the associated Profile is going to be destroyed.
  void Shutdown();

  // Look up an extension by ID. Does not include terminated
  // extensions.
  virtual const extensions::Extension* GetExtensionById(
      const std::string& id, bool include_disabled) const OVERRIDE;

  // Looks up an extension by ID, regardless of whether it's enabled,
  // disabled, blacklisted, or terminated.
  // DEPRECATED: Replace with:
  // ExtensionRegistry::GetExtensionById(id, ExtensionRegistry::EVERYTHING).
  virtual const extensions::Extension* GetInstalledExtension(
      const std::string& id) const OVERRIDE;

  // Updates a currently-installed extension with the contents from
  // |extension_path|.
  // TODO(aa): This method can be removed. ExtensionUpdater could use
  // CrxInstaller directly instead.
  virtual bool UpdateExtension(
      const std::string& id,
      const base::FilePath& extension_path,
      bool file_ownership_passed,
      const GURL& download_url,
      extensions::CrxInstaller** out_crx_installer) OVERRIDE;

  // Reloads the specified extension, sending the onLaunched() event to it if it
  // currently has any window showing.
  void ReloadExtension(const std::string extension_id);

  // Uninstalls the specified extension. Callers should only call this method
  // with extensions that exist. |external_uninstall| is a magical parameter
  // that is only used to send information to ExtensionPrefs, which external
  // callers should never set to true.
  //
  // We pass the |extension_id| by value to avoid having it deleted from under
  // us incase someone calls it with Extension::id() or another string that we
  // are going to delete in this function.
  //
  // TODO(aa): Remove |external_uninstall| -- this information should be passed
  // to ExtensionPrefs some other way.
  virtual bool UninstallExtension(std::string extension_id,
                                  bool external_uninstall,
                                  base::string16* error);

  virtual bool IsExtensionEnabled(
      const std::string& extension_id) const OVERRIDE;

  // Enables the extension.  If the extension is already enabled, does
  // nothing.
  virtual void EnableExtension(const std::string& extension_id);

  // Disables the extension.  If the extension is already disabled, or
  // cannot be disabled, does nothing.
  virtual void DisableExtension(const std::string& extension_id,
      extensions::Extension::DisableReason disable_reason);

  // Disable non-default and non-managed extensions with ids not in
  // |except_ids|. Default extensions are those from the Web Store with
  // |was_installed_by_default| flag.
  void DisableUserExtensions(const std::vector<std::string>& except_ids);

  // Updates the |extension|'s granted permissions lists to include all
  // permissions in the |extension|'s manifest and re-enables the
  // extension.
  void GrantPermissionsAndEnableExtension(
      const extensions::Extension* extension);

  // Updates the |extension|'s granted permissions lists to include all
  // permissions in the |extensions|'s manifest.
  void GrantPermissions(
      const extensions::Extension* extension);

  // Check for updates (or potentially new extensions from external providers)
  void CheckForExternalUpdates();

  // Unload the specified extension.
  virtual void UnloadExtension(
      const std::string& extension_id,
      extensions::UnloadedExtensionInfo::Reason reason) OVERRIDE;

  // Remove the specified component extension.
  virtual void RemoveComponentExtension(const std::string& extension_id)
      OVERRIDE;

  // Unload all extensions. Does not send notifications.
  void UnloadAllExtensionsForTest();

  // Reloads all extensions. Does not notify that extensions are ready.
  void ReloadExtensionsForTest();

  // Called when the initial extensions load has completed.
  virtual void OnLoadedInstalledExtensions();

  // Adds |extension| to this ExtensionService and notifies observers that the
  // extensions have been loaded.
  virtual void AddExtension(const extensions::Extension* extension) OVERRIDE;

  // Check if we have preferences for the component extension and, if not or if
  // the stored version differs, install the extension (without requirements
  // checking) before calling AddExtension.
  virtual void AddComponentExtension(const extensions::Extension* extension)
      OVERRIDE;

  enum ImportStatus {
   IMPORT_STATUS_OK,
   IMPORT_STATUS_UNSATISFIED,
   IMPORT_STATUS_UNRECOVERABLE
  };

  // Checks an extension's imports. No installed and outdated imports will be
  // stored in |missing_modules| and |outdated_modules|.
  ImportStatus CheckImports(
      const extensions::Extension* extension,
      std::list<extensions::SharedModuleInfo::ImportInfo>* missing_modules,
      std::list<extensions::SharedModuleInfo::ImportInfo>* outdated_modules);

  // Checks an extension's shared module imports to see if they are satisfied.
  // If they are not, this function adds the dependencies to the pending install
  // list if |extension| came from the webstore.
  ImportStatus SatisfyImports(const extensions::Extension* extension);

  // Returns a set of extensions that import a given extension.
  scoped_ptr<const extensions::ExtensionSet> GetDependentExtensions(
      const extensions::Extension* extension);

  // Uninstalls shared modules that were only referenced by |extension|.
  void PruneSharedModulesOnUninstall(const extensions::Extension* extension);

  // Informs the service that an extension's files are in place for loading.
  //
  // |page_ordinal| is the location of the extension in the app launcher.
  // |has_requirement_errors| is true if requirements of the extension weren't
  // met (for example graphics capabilities).
  // |blacklist_state| will be BLACKLISTED if the extension is blacklisted.
  // |wait_for_idle| may be false to install the extension immediately.
  void OnExtensionInstalled(
      const extensions::Extension* extension,
      const syncer::StringOrdinal& page_ordinal,
      bool has_requirement_errors,
      extensions::BlacklistState blacklist_state,
      bool wait_for_idle);

  // Checks for delayed installation for all pending installs.
  void MaybeFinishDelayedInstallations();

  // Similar to FinishInstallation, but first checks if there still is an update
  // pending for the extension, and makes sure the extension is still idle.
  void MaybeFinishDelayedInstallation(const std::string& extension_id);

  // Finishes installation of an update for an extension with the specified id,
  // when installation of that extension was previously delayed because the
  // extension was in use.
  virtual void FinishDelayedInstallation(
     const std::string& extension_id) OVERRIDE;

  // Returns an update for an extension with the specified id, if installation
  // of that update was previously delayed because the extension was in use. If
  // no updates are pending for the extension returns NULL.
  virtual const extensions::Extension* GetPendingExtensionUpdate(
      const std::string& extension_id) const OVERRIDE;

  // Go through each extension and unload those that are not allowed to run by
  // management policy providers (ie. network admin and Google-managed
  // blacklist).
  virtual void CheckManagementPolicy() OVERRIDE;

  virtual void CheckForUpdatesSoon() OVERRIDE;

  void set_extensions_enabled(bool enabled) { extensions_enabled_ = enabled; }
  bool extensions_enabled() { return extensions_enabled_; }

  void set_show_extensions_prompts(bool enabled) {
    show_extensions_prompts_ = enabled;
  }

  bool show_extensions_prompts() {
    return show_extensions_prompts_;
  }

  Profile* profile();

  // Returns profile_ as a BrowserContext.
  content::BrowserContext* GetBrowserContext() const;

  void set_extension_sync_service(
      ExtensionSyncService* extension_sync_service) {
    extension_sync_service_ = extension_sync_service;
  }

  // Whether the extension service is ready.
  virtual bool is_ready() OVERRIDE;

  virtual base::SequencedTaskRunner* GetFileTaskRunner() OVERRIDE;

  extensions::ComponentLoader* component_loader() {
    return component_loader_.get();
  }

  // Note that this may return NULL if autoupdate is not turned on.
  extensions::ExtensionUpdater* updater();

  // Notify the frontend that there was an error loading an extension.
  // This method is public because UnpackedInstaller and InstalledLoader
  // can post to here.
  // TODO(aa): Remove this. It doesn't do enough to be worth the dependency
  // of these classes on ExtensionService.
  void ReportExtensionLoadError(const base::FilePath& extension_path,
                                const std::string& error,
                                bool be_noisy);

  // Notifies ExtensionSettingsHandler whether or not to retry installation for
  // given |extension_path|.
  void NotifyLoadRetry(bool retry, const base::FilePath& extension_path);

  // ExtensionHost of background page calls this method right after its render
  // view has been created.
  void DidCreateRenderViewForBackgroundPage(extensions::ExtensionHost* host);

  // For the extension in |version_path| with |id|, check to see if it's an
  // externally managed extension.  If so, uninstall it.
  void CheckExternalUninstall(const std::string& id);

  // Changes sequenced task runner for crx installation tasks to |task_runner|.
  void SetFileTaskRunnerForTesting(base::SequencedTaskRunner* task_runner);

  // Clear all ExternalProviders.
  void ClearProvidersForTesting();

  // Adds an ExternalProviderInterface for the service to use during testing.
  // Takes ownership of |test_provider|.
  void AddProviderForTesting(
      extensions::ExternalProviderInterface* test_provider);

  // ExternalProvider::Visitor implementation.
  virtual bool OnExternalExtensionFileFound(
      const std::string& id,
      const base::Version* version,
      const base::FilePath& path,
      extensions::Manifest::Location location,
      int creation_flags,
      bool mark_acknowledged) OVERRIDE;

  virtual bool OnExternalExtensionUpdateUrlFound(
      const std::string& id,
      const std::string& install_parameter,
      const GURL& update_url,
      extensions::Manifest::Location location,
      int creation_flags,
      bool mark_acknowledged) OVERRIDE;

  virtual void OnExternalProviderReady(
      const extensions::ExternalProviderInterface* provider) OVERRIDE;

  // Returns true when all the external extension providers are ready.
  bool AreAllExternalProvidersReady() const;

  void OnAllExternalProvidersReady();

  // Once all external providers are done, generates any needed alerts about
  // extensions.
  void IdentifyAlertableExtensions();

  // Given an ExtensionErrorUI alert, populates it with any extensions that
  // need alerting. Returns true if the alert should be displayed at all.
  //
  // This method takes the extension_error_ui argument rather than using
  // the member variable to make it easier to test the method in isolation.
  bool PopulateExtensionErrorUI(ExtensionErrorUI* extension_error_ui);

  // Checks if there are any new external extensions to notify the user about.
  void UpdateExternalExtensionAlert();

  // Given a (presumably just-installed) extension id, mark that extension as
  // acknowledged.
  void AcknowledgeExternalExtension(const std::string& id);

  // Returns true if this extension is an external one that has yet to be
  // marked as acknowledged.
  bool IsUnacknowledgedExternalExtension(
      const extensions::Extension* extension);

  // Disable extensions that are known to be disabled yet are currently enabled.
  void ReconcileKnownDisabled();

  // Opens the Extensions page because the user wants to get more details
  // about the alerts.
  void HandleExtensionAlertDetails();

  // Called when the extension alert is closed. Updates prefs and deletes
  // the active |extension_error_ui_|.
  void HandleExtensionAlertClosed();

  // Marks alertable extensions as acknowledged, after the user presses the
  // accept button.
  void HandleExtensionAlertAccept();

  // content::NotificationObserver
  virtual void Observe(int type,
                       const content::NotificationSource& source,
                       const content::NotificationDetails& details) OVERRIDE;

  // Postpone installations so that we don't have to worry about race
  // conditions.
  void OnGarbageCollectIsolatedStorageStart();

  // Restart any extension installs which were delayed for isolated storage
  // garbage collection.
  void OnGarbageCollectIsolatedStorageFinished();

  // Record a histogram using the PermissionMessage enum values for each
  // permission in |e|.
  // NOTE: If this is ever called with high frequency, the implementation may
  // need to be made more efficient.
  static void RecordPermissionMessagesHistogram(
      const extensions::Extension* e, const char* histogram);

#if defined(UNIT_TEST)
  void TrackTerminatedExtensionForTest(const extensions::Extension* extension) {
    TrackTerminatedExtension(extension);
  }

  void FinishInstallationForTest(const extensions::Extension* extension) {
    FinishInstallation(extension);
  }
#endif

  base::WeakPtr<ExtensionService> AsWeakPtr() { return base::AsWeakPtr(this); }

  extensions::ExtensionGarbageCollector* garbage_collector() {
    return garbage_collector_.get();
  }

  bool browser_terminating() const { return browser_terminating_; }

  // For testing.
  void set_browser_terminating_for_test(bool value) {
    browser_terminating_ = value;
  }

  // By default ExtensionService will wait with installing an updated extension
  // until the extension is idle. Tests might not like this behavior, so you can
  // disable it with this method.
  void set_install_updates_when_idle_for_test(bool value) {
    install_updates_when_idle_ = value;
  }

  // Set a callback to be called when all external providers are ready and their
  // extensions have been installed.
  void set_external_updates_finished_callback_for_test(
      const base::Closure& callback) {
    external_updates_finished_callback_ = callback;
  }

  // Adds/Removes update observers.
  void AddUpdateObserver(extensions::UpdateObserver* observer);
  void RemoveUpdateObserver(extensions::UpdateObserver* observer);

 private:
  // Populates greylist_.
  void LoadGreylistFromPrefs();

  // Signals *ready_ and sends a notification to the listeners.
  void SetReadyAndNotifyListeners();

  // Return true if the sync type of |extension| matches |type|.
  void OnExtensionInstallPrefChanged();

  // Adds the given extension to the list of terminated extensions if
  // it is not already there and unloads it.
  void TrackTerminatedExtension(const extensions::Extension* extension);

  // Removes the extension with the given id from the list of
  // terminated extensions if it is there.
  void UntrackTerminatedExtension(const std::string& id);

  // Update preferences for a new or updated extension; notify observers that
  // the extension is installed, e.g., to update event handlers on background
  // pages; and perform other extension install tasks before calling
  // AddExtension.
  void AddNewOrUpdatedExtension(const extensions::Extension* extension,
                                extensions::Extension::State initial_state,
                                extensions::BlacklistState blacklist_state,
                                const syncer::StringOrdinal& page_ordinal,
                                const std::string& install_parameter);

  // Handles sending notification that |extension| was loaded.
  void NotifyExtensionLoaded(const extensions::Extension* extension);

  // Handles sending notification that |extension| was unloaded.
  void NotifyExtensionUnloaded(
      const extensions::Extension* extension,
      extensions::UnloadedExtensionInfo::Reason reason);

  // Common helper to finish installing the given extension.
  void FinishInstallation(const extensions::Extension* extension);

  // Updates the |extension|'s active permission set to include only permissions
  // currently requested by the extension and all the permissions required by
  // the extension.
  void UpdateActivePermissions(const extensions::Extension* extension);

  // Disables the extension if the privilege level has increased
  // (e.g., due to an upgrade).
  void CheckPermissionsIncrease(const extensions::Extension* extension,
                                bool is_extension_installed);

  // Helper that updates the active extension list used for crash reporting.
  void UpdateActiveExtensionsInCrashReporter();

  // Helper to determine whether we should initially enable an installed
  // (or upgraded) extension.
  bool ShouldEnableOnInstall(const extensions::Extension* extension);

  // Helper to determine if updating an extensions should proceed immediately,
  // or if we should delay the update until further notice.
  bool ShouldDelayExtensionUpdate(const std::string& extension_id,
                                  bool wait_for_idle) const;

  // extensions::Blacklist::Observer implementation.
  virtual void OnBlacklistUpdated() OVERRIDE;

  // Manages the blacklisted extensions, intended as callback from
  // Blacklist::GetBlacklistedIDs.
  void ManageBlacklist(
      const extensions::Blacklist::BlacklistStateMap& blacklisted_ids);

  // Add extensions in |blocked| to blacklisted_extensions, remove extensions
  // that are neither in |blocked|, nor in |unchanged|.
  void UpdateBlockedExtensions(const ExtensionIdSet& blocked,
                               const ExtensionIdSet& unchanged);

  void UpdateGreylistedExtensions(
      const ExtensionIdSet& greylist,
      const ExtensionIdSet& unchanged,
      const extensions::Blacklist::BlacklistStateMap& state_map);

  // Used only by test code.
  void UnloadAllExtensionsInternal();

  // The normal profile associated with this ExtensionService.
  Profile* profile_;

  // The ExtensionSystem for the profile above.
  extensions::ExtensionSystem* system_;

  // Preferences for the owning profile.
  extensions::ExtensionPrefs* extension_prefs_;

  // Blacklist for the owning profile.
  extensions::Blacklist* blacklist_;

  // The ExtensionSyncService that is used by this ExtensionService.
  ExtensionSyncService* extension_sync_service_;

  // Sets of enabled/disabled/terminated/blacklisted extensions. Not owned.
  extensions::ExtensionRegistry* registry_;

  // Set of greylisted extensions. These extensions are disabled if they are
  // already installed in Chromium at the time when they are added to
  // the greylist. Unlike blacklisted extensions, greylisted ones are visible
  // to the user and if user re-enables such an extension, they remain enabled.
  //
  // These extensions should appear in registry_.
  extensions::ExtensionSet greylist_;

  // The list of extension installs delayed for various reasons.  The reason
  // for delayed install is stored in ExtensionPrefs. These are not part of
  // ExtensionRegistry because they are not yet installed.
  extensions::ExtensionSet delayed_installs_;

  // Hold the set of pending extensions.
  extensions::PendingExtensionManager pending_extension_manager_;

  // The full path to the directory where extensions are installed.
  base::FilePath install_directory_;

  // Whether or not extensions are enabled.
  bool extensions_enabled_;

  // Whether to notify users when they attempt to install an extension.
  bool show_extensions_prompts_;

  // Whether to delay installing of extension updates until the extension is
  // idle.
  bool install_updates_when_idle_;

  // Signaled when all extensions are loaded.
  extensions::OneShotEvent* const ready_;

  // Our extension updater, if updates are turned on.
  scoped_ptr<extensions::ExtensionUpdater> updater_;

  // Map unloaded extensions' ids to their paths. When a temporarily loaded
  // extension is unloaded, we lose the information about it and don't have
  // any in the extension preferences file.
  typedef std::map<std::string, base::FilePath> UnloadedExtensionPathMap;
  UnloadedExtensionPathMap unloaded_extension_paths_;

  // Store the ids of reloading extensions.
  std::set<std::string> reloading_extensions_;

  // Map of DevToolsAgentHost instances that are detached,
  // waiting for an extension to be reloaded.
  typedef std::map<std::string, scoped_refptr<content::DevToolsAgentHost> >
      OrphanedDevTools;
  OrphanedDevTools orphaned_dev_tools_;

  content::NotificationRegistrar registrar_;
  PrefChangeRegistrar pref_change_registrar_;

  // Keeps track of loading and unloading component extensions.
  scoped_ptr<extensions::ComponentLoader> component_loader_;

  // A collection of external extension providers.  Each provider reads
  // a source of external extension information.  Examples include the
  // windows registry and external_extensions.json.
  extensions::ProviderCollection external_extension_providers_;

  // Set to true by OnExternalExtensionUpdateUrlFound() when an external
  // extension URL is found, and by CheckForUpdatesSoon() when an update check
  // has to wait for the external providers.  Used in
  // OnAllExternalProvidersReady() to determine if an update check is needed to
  // install pending extensions.
  bool update_once_all_providers_are_ready_;

  // A callback to be called when all external providers are ready and their
  // extensions have been installed. Normally this is a null callback, but
  // is used in external provider related tests.
  base::Closure external_updates_finished_callback_;

  // Set when the browser is terminating. Prevents us from installing or
  // updating additional extensions and allows in-progress installations to
  // decide to abort.
  bool browser_terminating_;

  // Set to true to delay all new extension installations. Acts as a lock to
  // allow background processing of garbage collection of on-disk state without
  // needing to worry about race conditions caused by extension installation and
  // reinstallation.
  bool installs_delayed_for_gc_;

  // Set to true if this is the first time this ExtensionService has run.
  // Used for specially handling external extensions that are installed the
  // first time.
  bool is_first_run_;

  // A set of the extension ids currently being reloaded.  We use this to
  // avoid showing a "new install" notice for an extension reinstall.
  std::set<std::string> extensions_being_reloaded_;

  // A set of the extension ids currently being terminated. We use this to
  // avoid trying to unload the same extension twice.
  std::set<std::string> extensions_being_terminated_;

  scoped_ptr<ExtensionErrorUI> extension_error_ui_;
  // Sequenced task runner for extension related file operations.
  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;

#if defined(ENABLE_EXTENSIONS)
  scoped_ptr<extensions::ExtensionActionStorageManager>
      extension_action_storage_manager_;
#endif
  scoped_ptr<extensions::ManagementPolicy::Provider>
      shared_module_policy_provider_;

  // The ExtensionGarbageCollector to clean up all the garbage that leaks into
  // the extensions directory.
  scoped_ptr<extensions::ExtensionGarbageCollector> garbage_collector_;

  ObserverList<extensions::UpdateObserver, true> update_observers_;

  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           InstallAppsWithUnlimtedStorage);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           InstallAppsAndCheckStorageProtection);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest, SetUnsetBlacklistInPrefs);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           BlacklistedExtensionWillNotInstall);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           UnloadBlacklistedExtensionPolicy);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           WillNotLoadBlacklistedExtensionsFromDirectory);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           BlacklistedInPrefsFromStartup);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           GreylistedExtensionDisabled);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           GreylistDontEnableManuallyDisabled);
  FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                           GreylistUnknownDontChange);
  DISALLOW_COPY_AND_ASSIGN(ExtensionService);
};

#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SERVICE_H_