Use a direct include of the message_loop header in base/.

base/run_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_RUN_LOOP_H_
 #define BASE_RUN_LOOP_H_
 
 #include "base/base_export.h"
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 
 namespace base {
 #if defined(OS_ANDROID)
 class MessagePumpForUI;
 #endif
 
 #if defined(OS_IOS)
 class MessagePumpUIApplication;
 #endif
 
@@ skipping 90 matching lines @@
   // Used to record that QuitWhenIdle() was called on the MessageLoop, meaning
   // that we should quit Run once it becomes idle.
   bool quit_when_idle_received_;
 
   DISALLOW_COPY_AND_ASSIGN(RunLoop);
 };
 
 }  // namespace base
 
 #endif  // BASE_RUN_LOOP_H_