Move most of the remaining users of WebContentsObserver::tab_contents() to use web_contents().

chrome/browser/ui/prefs/prefs_tab_helper.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 CHROME_BROWSER_UI_PREFS_PREFS_TAB_HELPER_H_
 #define CHROME_BROWSER_UI_PREFS_PREFS_TAB_HELPER_H_
 #pragma once
 
 #include "chrome/browser/prefs/pref_change_registrar.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_contents_observer.h"
 
 class PrefService;
 class Profile;
 struct WebPreferences;
 
 // Per-tab class to handle user preferences.
 class PrefsTabHelper : public content::WebContentsObserver,
                        public content::NotificationObserver {
  public:
-  explicit PrefsTabHelper(TabContents* contents);
+  explicit PrefsTabHelper(content::WebContents* contents);
   virtual ~PrefsTabHelper();
 
   static void RegisterUserPrefs(PrefService* prefs);
 
   PrefService* per_tab_prefs() { return per_tab_prefs_.get(); }
 
  protected:
   // Update the RenderView's WebPreferences. Exposed as protected for testing.
   virtual void UpdateWebPreferences();
 
   // content::WebContentsObserver overrides, exposed as protected for testing.
   virtual void RenderViewCreated(RenderViewHost* render_view_host) OVERRIDE;
 
  private:
   // content::WebContentsObserver overrides:
   virtual void WebContentsDestroyed(content::WebContents* tab) OVERRIDE;
 
   // content::NotificationObserver overrides:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // Update the TabContents's RendererPreferences.
   void UpdateRendererPreferences();
 
   Profile* GetProfile();
 
-  // Our owning TabContents.
-  TabContents* contents_;
-
   content::NotificationRegistrar registrar_;
 
   scoped_ptr<PrefService> per_tab_prefs_;
   PrefChangeRegistrar pref_change_registrar_;
   PrefChangeRegistrar per_tab_pref_change_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefsTabHelper);
 };
 
 #endif  // CHROME_BROWSER_UI_PREFS_PREFS_TAB_HELPER_H_