Move message_pump to base/message_loop.
This also fixes some namespace usage inside the message pump files and updates all users of these files to use the new location.
Reland of 206507.
Original review https://codereview.chromium.org/17078005/
TBR=sky
Review URL: https://codereview.chromium.org/16897006
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@207075 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/message_loop/message_pump.h b/base/message_loop/message_pump.h
new file mode 100644
index 0000000..5b72232
--- /dev/null
+++ b/base/message_loop/message_pump.h
@@ -0,0 +1,129 @@
+// 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 BASE_MESSAGE_LOOP_MESSAGE_PUMP_H_
+#define BASE_MESSAGE_LOOP_MESSAGE_PUMP_H_
+
+#include "base/base_export.h"
+#include "base/memory/ref_counted.h"
+
+namespace base {
+
+class TimeTicks;
+
+class BASE_EXPORT MessagePump : public RefCountedThreadSafe<MessagePump> {
+ public:
+ // Please see the comments above the Run method for an illustration of how
+ // these delegate methods are used.
+ class BASE_EXPORT Delegate {
+ public:
+ virtual ~Delegate() {}
+
+ // Called from within Run in response to ScheduleWork or when the message
+ // pump would otherwise call DoDelayedWork. Returns true to indicate that
+ // work was done. DoDelayedWork will still be called if DoWork returns
+ // true, but DoIdleWork will not.
+ virtual bool DoWork() = 0;
+
+ // Called from within Run in response to ScheduleDelayedWork or when the
+ // message pump would otherwise sleep waiting for more work. Returns true
+ // to indicate that delayed work was done. DoIdleWork will not be called
+ // if DoDelayedWork returns true. Upon return |next_delayed_work_time|
+ // indicates the time when DoDelayedWork should be called again. If
+ // |next_delayed_work_time| is null (per Time::is_null), then the queue of
+ // future delayed work (timer events) is currently empty, and no additional
+ // calls to this function need to be scheduled.
+ virtual bool DoDelayedWork(TimeTicks* next_delayed_work_time) = 0;
+
+ // Called from within Run just before the message pump goes to sleep.
+ // Returns true to indicate that idle work was done.
+ virtual bool DoIdleWork() = 0;
+ };
+
+ MessagePump();
+
+ // The Run method is called to enter the message pump's run loop.
+ //
+ // Within the method, the message pump is responsible for processing native
+ // messages as well as for giving cycles to the delegate periodically. The
+ // message pump should take care to mix delegate callbacks with native
+ // message processing so neither type of event starves the other of cycles.
+ //
+ // The anatomy of a typical run loop:
+ //
+ // for (;;) {
+ // bool did_work = DoInternalWork();
+ // if (should_quit_)
+ // break;
+ //
+ // did_work |= delegate_->DoWork();
+ // if (should_quit_)
+ // break;
+ //
+ // TimeTicks next_time;
+ // did_work |= delegate_->DoDelayedWork(&next_time);
+ // if (should_quit_)
+ // break;
+ //
+ // if (did_work)
+ // continue;
+ //
+ // did_work = delegate_->DoIdleWork();
+ // if (should_quit_)
+ // break;
+ //
+ // if (did_work)
+ // continue;
+ //
+ // WaitForWork();
+ // }
+ //
+ // Here, DoInternalWork is some private method of the message pump that is
+ // responsible for dispatching the next UI message or notifying the next IO
+ // completion (for example). WaitForWork is a private method that simply
+ // blocks until there is more work of any type to do.
+ //
+ // Notice that the run loop cycles between calling DoInternalWork, DoWork,
+ // and DoDelayedWork methods. This helps ensure that none of these work
+ // queues starve the others. This is important for message pumps that are
+ // used to drive animations, for example.
+ //
+ // Notice also that after each callout to foreign code, the run loop checks
+ // to see if it should quit. The Quit method is responsible for setting this
+ // flag. No further work is done once the quit flag is set.
+ //
+ // NOTE: Care must be taken to handle Run being called again from within any
+ // of the callouts to foreign code. Native message pumps may also need to
+ // deal with other native message pumps being run outside their control
+ // (e.g., the MessageBox API on Windows pumps UI messages!). To be specific,
+ // the callouts (DoWork and DoDelayedWork) MUST still be provided even in
+ // nested sub-loops that are "seemingly" outside the control of this message
+ // pump. DoWork in particular must never be starved for time slices unless
+ // it returns false (meaning it has run out of things to do).
+ //
+ virtual void Run(Delegate* delegate) = 0;
+
+ // Quit immediately from the most recently entered run loop. This method may
+ // only be used on the thread that called Run.
+ virtual void Quit() = 0;
+
+ // Schedule a DoWork callback to happen reasonably soon. Does nothing if a
+ // DoWork callback is already scheduled. This method may be called from any
+ // thread. Once this call is made, DoWork should not be "starved" at least
+ // until it returns a value of false.
+ virtual void ScheduleWork() = 0;
+
+ // Schedule a DoDelayedWork callback to happen at the specified time,
+ // cancelling any pending DoDelayedWork callback. This method may only be
+ // used on the thread that called Run.
+ virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) = 0;
+
+ protected:
+ virtual ~MessagePump();
+ friend class RefCountedThreadSafe<MessagePump>;
+};
+
+} // namespace base
+
+#endif // BASE_MESSAGE_LOOP_MESSAGE_PUMP_H_
