Revert 110262 - Have ExtensionHost use TabContents instead of RenderViewHost. Try #2.

content/browser/tab_contents/tab_contents_observer.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.
 
 #ifndef CONTENT_BROWSER_TAB_CONTENTS_TAB_CONTENTS_OBSERVER_H_
 #define CONTENT_BROWSER_TAB_CONTENTS_TAB_CONTENTS_OBSERVER_H_
 
 #include "base/process_util.h"
 #include "content/browser/tab_contents/navigation_controller.h"
 #include "content/common/content_export.h"
@@ skipping 35 matching lines @@
   virtual void DidCommitProvisionalLoadForFrame(
       int64 frame_id,
       bool is_main_frame,
       const GURL& url,
       content::PageTransition transition_type);
   virtual void DidFailProvisionalLoad(int64 frame_id,
                                       bool is_main_frame,
                                       const GURL& validated_url,
                                       int error_code,
                                       const string16& error_description);
-  virtual void DocumentAvailableInMainFrame();
   virtual void DocumentLoadedInFrame(int64 frame_id);
   virtual void DidFinishLoad(int64 frame_id);
   virtual void DidGetUserGesture();
   virtual void DidGetIgnoredUIEvent();
   virtual void DidBecomeSelected();
 
   virtual void DidStartLoading();
   virtual void DidStopLoading();
   virtual void StopNavigation();
 
@@ skipping 61 matching lines @@
   // Invoked from TabContents. Invokes TabContentsDestroyed and NULL out
   // |tab_contents_|.
   void TabContentsDestroyed();
 
   TabContents* tab_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(TabContentsObserver);
 };
 
 #endif  // CONTENT_BROWSER_TAB_CONTENTS_TAB_CONTENTS_OBSERVER_H_