Move Singleton and related structs to namespace base

content/browser/histogram_synchronizer.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_SYNCHRONIZER_H_
 #define CONTENT_BROWSER_HISTOGRAM_SYNCHRONIZER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 57 matching lines @@
 
   // Contact all child 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.
   static void FetchHistogramsAsynchronously(base::MessageLoop* callback_thread,
                                             const base::Closure& callback,
                                             base::TimeDelta wait_time);
 
  private:
-  friend struct DefaultSingletonTraits<HistogramSynchronizer>;
+  friend struct base::DefaultSingletonTraits<HistogramSynchronizer>;
 
   class RequestContext;
 
   HistogramSynchronizer();
   ~HistogramSynchronizer() override;
 
   // Establish a new sequence number, and use it to notify all processes
   // (renderers, plugins, GPU, etc) of the need to supply, to the browser,
   // any/all changes to their histograms. |wait_time| specifies the amount of
   // time to wait before cancelling the requests for non-responsive processes.
@@ skipping 56 matching lines @@
   // The sequence number used by the most recent asynchronous update request to
   // contact all processes.
   int async_sequence_number_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramSynchronizer);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_HISTOGRAM_SYNCHRONIZER_H_