Add a new GetInstance() method for singleton classes used in chrome/browser files.

chrome/browser/cross_site_request_manager.h

 // Copyright (c) 2010 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 CHROME_BROWSER_CROSS_SITE_REQUEST_MANAGER_H__
 #define CHROME_BROWSER_CROSS_SITE_REQUEST_MANAGER_H__
 #pragma once
 
 #include <set>
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/lock.h"
-#include "base/singleton.h"
+
+template <typename T> struct DefaultSingletonTraits;
 
 // CrossSiteRequestManager is used to handle bookkeeping for cross-site
 // requests and responses between the UI and IO threads.  Such requests involve
 // a transition from one RenderViewHost to another within TabContents, and
 // involve coordination with ResourceDispatcherHost.
 //
 // CrossSiteRequestManager is a singleton that may be used on any thread.
 //
 class CrossSiteRequestManager {
  public:
+  // Returns the singleton instance.
+  static CrossSiteRequestManager* GetInstance();
+
   // Returns whether the RenderViewHost specified by the given IDs currently
   // has a pending cross-site request.  If so, we will have to delay the
   // response until the previous RenderViewHost runs its onunload handler.
   // Called by ResourceDispatcherHost on the IO thread.
   bool HasPendingCrossSiteRequest(int renderer_id, int render_view_id);
 
   // Sets whether the RenderViewHost specified by the given IDs currently has a
   // pending cross-site request.  Called by RenderViewHost on the UI thread.
   void SetHasPendingCrossSiteRequest(int renderer_id,
                                      int render_view_id,
                                      bool has_pending);
 
  private:
   friend struct DefaultSingletonTraits<CrossSiteRequestManager>;
   typedef std::set<std::pair<int, int> > RenderViewSet;
 
-  // Obtain an instance of CrossSiteRequestManager via
-  // Singleton<CrossSiteRequestManager>().
   CrossSiteRequestManager();
   ~CrossSiteRequestManager();
 
   // You must acquire this lock before reading or writing any members of this
   // class.  You must not block while holding this lock.
   Lock lock_;
 
   // Set of (render_process_host_id, render_view_id) pairs of all
   // RenderViewHosts that have pending cross-site requests.  Used to pass
   // information about the RenderViewHosts between the UI and IO threads.
   RenderViewSet pending_cross_site_views_;
 
   DISALLOW_COPY_AND_ASSIGN(CrossSiteRequestManager);
 };
 
 #endif  // CHROME_BROWSER_CROSS_SITE_REQUEST_MANAGER_H__