Move MessageLoop to base namespace.

content/public/browser/histogram_fetcher.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 CONTENT_PUBLIC_BROWSER_HISTOGRAM_FETCHER_H_
 #define CONTENT_PUBLIC_BROWSER_HISTOGRAM_FETCHER_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/time.h"
 #include "content/common/content_export.h"
 
+namespace base {
 class MessageLoop;
+}
 
 namespace content {
 
 // Fetch histogram data asynchronously from the various child processes, into
 // the browser process. This method is used by the metrics services in
 // preparation for a log upload. It contacts all processes, and get them to
 // upload to the browser any/all changes to histograms.  When all changes have
 // been acquired, or when the wait time expires (whichever is sooner), post the
 // callback to the specified message loop. Note the callback is posted exactly
 // once.
-CONTENT_EXPORT void FetchHistogramsAsynchronously(MessageLoop* callback_thread,
-                                                  const base::Closure& callback,
-                                                  base::TimeDelta wait_time);
+CONTENT_EXPORT void FetchHistogramsAsynchronously(
+    base::MessageLoop* callback_thread,
+    const base::Closure& callback,
+    base::TimeDelta wait_time);
+
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_HISTOGRAM_FETCHER_H_