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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_UI_ALTERNATE_ERROR_TAB_OBSERVER_H_
      6 #define CHROME_BROWSER_UI_ALTERNATE_ERROR_TAB_OBSERVER_H_
      7 
      8 #include "base/prefs/pref_change_registrar.h"
      9 #include "content/public/browser/notification_observer.h"
     10 #include "content/public/browser/notification_registrar.h"
     11 #include "content/public/browser/web_contents_observer.h"
     12 #include "content/public/browser/web_contents_user_data.h"
     13 
     14 class Profile;
     15 
     16 namespace user_prefs {
     17 class PrefRegistrySyncable;
     18 }
     19 
     20 // Per-tab class to implement alternate error page functionality.
     21 class AlternateErrorPageTabObserver
     22     : public content::WebContentsObserver,
     23       public content::NotificationObserver,
     24       public content::WebContentsUserData<AlternateErrorPageTabObserver> {
     25  public:
     26   virtual ~AlternateErrorPageTabObserver();
     27 
     28   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
     29 
     30  private:
     31   explicit AlternateErrorPageTabObserver(content::WebContents* web_contents);
     32   friend class content::WebContentsUserData<AlternateErrorPageTabObserver>;
     33 
     34   // content::WebContentsObserver overrides:
     35   virtual void RenderViewCreated(
     36       content::RenderViewHost* render_view_host) OVERRIDE;
     37 
     38   // content::NotificationObserver overrides:
     39   virtual void Observe(int type,
     40                        const content::NotificationSource& source,
     41                        const content::NotificationDetails& details) OVERRIDE;
     42 
     43   // Internal helpers ----------------------------------------------------------
     44 
     45   // Returns the server that can provide alternate error pages.  If the returned
     46   // URL is empty, the default error page built into WebKit will be used.
     47   GURL GetAlternateErrorPageURL() const;
     48 
     49   void OnAlternateErrorPagesEnabledChanged();
     50 
     51   // Send the alternate error page URL to the renderer.
     52   void UpdateAlternateErrorPageURL(content::RenderViewHost* rvh);
     53 
     54   Profile* profile_;
     55   content::NotificationRegistrar registrar_;
     56   PrefChangeRegistrar pref_change_registrar_;
     57 
     58   DISALLOW_COPY_AND_ASSIGN(AlternateErrorPageTabObserver);
     59 };
     60 
     61 #endif  // CHROME_BROWSER_UI_ALTERNATE_ERROR_TAB_OBSERVER_H_
     62