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

chrome/browser/cross_site_request_manager.cc

 // Copyright (c) 2006-2008 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.
 
 #include "chrome/browser/cross_site_request_manager.h"
 
 bool CrossSiteRequestManager::HasPendingCrossSiteRequest(int renderer_id,
                                                          int render_view_id) {
   AutoLock lock(lock_);
 
@@ skipping 11 matching lines @@
   if (has_pending) {
     pending_cross_site_views_.insert(key);
   } else {
     pending_cross_site_views_.erase(key);
   }
 }
 
 CrossSiteRequestManager::CrossSiteRequestManager() {}
 
 CrossSiteRequestManager::~CrossSiteRequestManager() {}
+
+// static
+CrossSiteRequestManager* CrossSiteRequestManager::GetInstance() {
+  return Singleton<CrossSiteRequestManager>::get();
+}