Add observer interface to PrerenderContents.

chrome/browser/prerender/prerender_manager.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 CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 
 #include <list>
 #include <map>
 #include <string>
@@ skipping 163 matching lines @@
   // Controls if we launch or squash prefetch requests as they arrive from
   // renderers.
   static bool IsPrefetchEnabled();
   static void SetIsPrefetchEnabled(bool enabled);
 
   static PrerenderManagerMode GetMode();
   static void SetMode(PrerenderManagerMode mode);
   static const char* GetModeString();
   static bool IsPrerenderingPossible();
   static bool ActuallyPrerendering();
-  static bool IsControlGroup();
+  static bool IsControlGroup(uint8 experiment_id);
   static bool IsNoUseGroup();
 
   // Query the list of current prerender pages to see if the given web contents
   // is prerendering a page. The optional parameter |origin| is an output
   // parameter which, if a prerender is found, is set to the Origin of the
   // prerender |web_contents|.
   bool IsWebContentsPrerendering(content::WebContents* web_contents,
                                  Origin* origin) const;
 
   // Returns the PrerenderContents object for the given web_contents if it's
@@ skipping 385 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderManager);
 };
 
 PrerenderManager* FindPrerenderManagerUsingRenderProcessId(
     int render_process_id);
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_