Move Singleton and related structs to namespace base

content/browser/histogram_controller.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_BROWSER_HISTOGRAM_CONTROLLER_H_
 #define CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 37 matching lines @@
   // increase.  This is called on the UI thread.
   void OnPendingProcesses(int sequence_number, int pending_processes, bool end);
 
   // Send the |histogram| back to the |subscriber_|.
   // This can be called from any thread.
   void OnHistogramDataCollected(
       int sequence_number,
       const std::vector<std::string>& pickled_histograms);
 
  private:
-  friend struct DefaultSingletonTraits<HistogramController>;
+  friend struct base::DefaultSingletonTraits<HistogramController>;
 
   // Contact PLUGIN and GPU child processes and get their histogram data.
   // TODO(rtenneti): Enable getting histogram data for other processes like
   // PPAPI and NACL.
   void GetHistogramDataFromChildProcesses(int sequence_number);
 
   HistogramSubscriber* subscriber_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_