Move MessageLoop to base namespace.

base/timer.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.
 
 // OneShotTimer and RepeatingTimer provide a simple timer API.  As the names
 // suggest, OneShotTimer calls you back once after a time delay expires.
 // RepeatingTimer on the other hand calls you back periodically with the
 // prescribed time interval.
 //
 // OneShotTimer and RepeatingTimer both cancel the timer when they go out of
@@ skipping 38 matching lines @@
 // because they're flaky on the buildbot, but when you run them locally you
 // should be able to tell the difference.
 
 #include "base/base_export.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/time.h"
 
-class MessageLoop;
-
 namespace base {
 
 class BaseTimerTaskInternal;
+class MessageLoop;
 
 //-----------------------------------------------------------------------------
 // This class wraps MessageLoop::PostDelayedTask to manage delayed and repeating
 // tasks. It must be destructed on the same thread that starts tasks. There are
 // DCHECKs in place to verify this.
 //
 class BASE_EXPORT Timer {
  public:
   // Construct a timer in repeating or one-shot mode. Start or SetTaskInfo must
   // be called later to set task info. |retain_user_task| determines whether the
@@ skipping 164 matching lines @@
       : Timer(posted_from, delay,
               base::Bind(method, base::Unretained(receiver)),
               false) {}
 
   void Reset() { Timer::Reset(); }
 };
 
 }  // namespace base
 
 #endif  // BASE_TIMER_H_