Add base::ThreadTaskRunner class.

base/message_loop.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_H_
 #define BASE_MESSAGE_LOOP_H_
 #pragma once
 
 #include <queue>
 #include <string>
@@ skipping 24 matching lines @@
 #include "base/message_pump_x.h"
 #else
 #include "base/message_pump_gtk.h"
 #endif
 
 #endif
 #endif
 
 namespace base {
 class Histogram;
-}
+class ThreadTaskRunnerHandle;
+}  // namespace base
 
 // A MessageLoop is used to process events for a particular thread.  There is
 // at most one MessageLoop instance per thread.
 //
 // Events include at a minimum Task instances submitted to PostTask or those
 // managed by TimerManager.  Depending on the type of message pump used by the
 // MessageLoop other events such as UI messages may be processed.  On Windows
 // APC calls (as time permits) and signals sent to a registered set of HANDLEs
 // may also be processed.
 //
@@ skipping 454 matching lines @@
   // Should be set to true before calling Windows APIs like TrackPopupMenu, etc
   // which enter a modal message loop.
   bool os_modal_loop_;
 #endif
 
   // The next sequence number to use for delayed tasks.
   int next_sequence_num_;
 
   ObserverList<TaskObserver> task_observers_;
 
   // The message loop proxy associated with this message loop, if one exists.

[willchan no longer on Chromium, 2012/05/08 02:35:06]

Can we construct these guys in the initializer list and make them const? There's
no reason for ThreadTaskRunnerHandle to be scoped_ptr and non-const, right?

[Sergey Ulanov, 2012/05/09 18:34:11]

I thought about it - problem is that MessageLoopProxyImpl depends on
MessageLoop::current() and so it must be created only after current() is set.

[willchan no longer on Chromium, 2012/05/09 18:38:48]

Good point. OK.

   scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
+  scoped_ptr<base::ThreadTaskRunnerHandle> thread_task_runner_handle_;
 
  private:
   template <class T, class R> friend class base::subtle::DeleteHelperInternal;
   template <class T, class R> friend class base::subtle::ReleaseHelperInternal;
 
   void DeleteSoonInternal(const tracked_objects::Location& from_here,
                           void(*deleter)(const void*),
                           const void* object);
   void ReleaseSoonInternal(const tracked_objects::Location& from_here,
                            void(*releaser)(const void*),
@@ skipping 125 matching lines @@
 #endif  // defined(OS_POSIX)
 };
 
 // Do not add any member variables to MessageLoopForIO!  This is important b/c
 // MessageLoopForIO is often allocated via MessageLoop(TYPE_IO).  Any extra
 // data that you need should be stored on the MessageLoop's pump_ instance.
 COMPILE_ASSERT(sizeof(MessageLoop) == sizeof(MessageLoopForIO),
                MessageLoopForIO_should_not_have_extra_member_variables);
 
 #endif  // BASE_MESSAGE_LOOP_H_