Trying changes to see the perfomance impact on Mac....

chrome/browser/browser_process.h

 // Copyright (c) 2011 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.
 
 // This interface is for managing the global services of the application. Each
 // service is lazily created when requested the first time. The service getters
 // will return NULL if the service is not available, so callers must check for
 // this condition.
 
 #ifndef CHROME_BROWSER_BROWSER_PROCESS_H_
@@ skipping 21 matching lines @@
 class IntranetRedirectDetector;
 class IOThread;
 class MetricsService;
 class NotificationUIManager;
 class PrefService;
 class ProfileManager;
 class ResourceDispatcherHost;
 class SidebarManager;
 class TabCloseableStateWatcher;
 class ThumbnailGenerator;
+class WatchDogThread;
 
 namespace base {
 class Thread;
 class WaitableEvent;
 }
 
 namespace printing {
 class PrintJobManager;
 class PrintPreviewTabController;
 }
@@ skipping 56 matching lines @@
 
 #if defined(USE_X11)
   // Returns the thread that is used to process UI requests in cases where
   // we can't route the request to the UI thread. Note that this thread
   // should only be used by the IO thread and this method is only safe to call
   // from the UI thread so, if you've ended up here, something has gone wrong.
   // This method is only included for uniformity.
   virtual base::Thread* background_x11_thread() = 0;
 #endif
 
+  // Returns the thread that is used for health check of all browser threads.
+  virtual WatchDogThread* watchdog_thread() = 0;
+
   virtual policy::BrowserPolicyConnector* browser_policy_connector() = 0;
 
   virtual IconManager* icon_manager() = 0;
 
   virtual ThumbnailGenerator* GetThumbnailGenerator() = 0;
 
   virtual AutomationProviderList* InitAutomationProviderList() = 0;
 
   virtual void InitDevToolsHttpProtocolHandler(
       const std::string& ip,
@@ skipping 84 matching lines @@
 
   // Used for testing plugin data removal at shutdown.
   std::string plugin_data_remover_mime_type_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserProcess);
 };
 
 extern BrowserProcess* g_browser_process;
 
 #endif  // CHROME_BROWSER_BROWSER_PROCESS_H_