Move MessageLoop to base namespace.

sync/engine/sync_scheduler.h

 // Copyright 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.
 //
 // A class to schedule syncer tasks intelligently.
 #ifndef SYNC_ENGINE_SYNC_SCHEDULER_H_
 #define SYNC_ENGINE_SYNC_SCHEDULER_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/time.h"
 #include "sync/base/sync_export.h"
 #include "sync/engine/nudge_source.h"
 #include "sync/internal_api/public/base/model_type_invalidation_map.h"
 #include "sync/sessions/sync_session.h"
 
-class MessageLoop;
-
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
 namespace syncer {
 
 struct ServerConnectionEvent;
 
 struct SYNC_EXPORT_PRIVATE ConfigurationParams {
   ConfigurationParams();
@@ skipping 79 matching lines @@
   // Called when credentials are updated by the user.
   virtual void OnCredentialsUpdated() = 0;
 
   // Called when the network layer detects a connection status change.
   virtual void OnConnectionStatusChange() = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_SYNC_SCHEDULER_H_