Revert 206507 "Move message_pump to base/message_loop."

trunk/src/base/message_loop/message_pump.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 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_