Move Singleton and related structs to namespace base

content/browser/accessibility/ax_tree_id_registry.h

 // Copyright 2014 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_ACCESSIBILITY_AX_TREE_ID_REGISTRY_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_AX_TREE_ID_REGISTRY_H_
 
 #include <map>
 
 #include "base/stl_util.h"
-
+namespace base {
 template <typename T>
 struct DefaultSingletonTraits;
+}  // namespace base
 
 namespace content {
 
 // A class which generates a unique id given a process id and frame routing id.
 class AXTreeIDRegistry {
  public:
   typedef std::pair<int, int> FrameID;
 
   typedef int AXTreeID;
 
   static const AXTreeID kNoAXTreeID;
 
   // Get the single instance of this class.
   static AXTreeIDRegistry* GetInstance();
 
   // Obtains a unique id given a |process_id| and |routing_id|. Placeholder
   // for full implementation once out of process iframe accessibility finalizes.
   AXTreeID GetOrCreateAXTreeID(int process_id, int routing_id);
   FrameID GetFrameID(AXTreeID ax_tree_id);
   void RemoveAXTreeID(AXTreeID ax_tree_id);
 
  private:
-  friend struct DefaultSingletonTraits<AXTreeIDRegistry>;
+  friend struct base::DefaultSingletonTraits<AXTreeIDRegistry>;
 
   AXTreeIDRegistry();
   virtual ~AXTreeIDRegistry();
 
   // Tracks the current unique ax frame id.
   AXTreeID ax_tree_id_counter_;
 
   // Maps an accessibility tree to its frame via ids.
   std::map<AXTreeID, FrameID> ax_tree_to_frame_id_map_;
 
   // Maps frames to an accessibility tree via ids.
   std::map<FrameID, AXTreeID> frame_to_ax_tree_id_map_;
 
   DISALLOW_COPY_AND_ASSIGN(AXTreeIDRegistry);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_AX_TREE_ID_REGISTRY_H_