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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_THUMBNAILS_THUMBNAIL_TAB_HELPER_H_
      6 #define CHROME_BROWSER_THUMBNAILS_THUMBNAIL_TAB_HELPER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "chrome/browser/thumbnails/thumbnailing_context.h"
     10 #include "content/public/browser/notification_observer.h"
     11 #include "content/public/browser/notification_registrar.h"
     12 #include "content/public/browser/web_contents_observer.h"
     13 #include "content/public/browser/web_contents_user_data.h"
     14 
     15 namespace content {
     16 class RenderViewHost;
     17 class RenderWidgetHost;
     18 }
     19 
     20 class ThumbnailTabHelper
     21     : public content::NotificationObserver,
     22       public content::WebContentsObserver,
     23       public content::WebContentsUserData<ThumbnailTabHelper> {
     24  public:
     25   virtual ~ThumbnailTabHelper();
     26 
     27   // Enables or disables the function of taking thumbnails.
     28   // A disabled ThumbnailTabHelper generates no thumbnails although it still
     29   // continues to receive the notifications from the web contents.
     30   void set_enabled(bool enabled) { enabled_ = enabled; }
     31 
     32  private:
     33   explicit ThumbnailTabHelper(content::WebContents* contents);
     34   friend class content::WebContentsUserData<ThumbnailTabHelper>;
     35 
     36   // content::NotificationObserver overrides.
     37   virtual void Observe(int type,
     38                        const content::NotificationSource& source,
     39                        const content::NotificationDetails& details) OVERRIDE;
     40 
     41   // content::WebContentsObserver overrides.
     42   virtual void RenderViewDeleted(
     43       content::RenderViewHost* render_view_host) OVERRIDE;
     44   virtual void DidStartLoading(
     45       content::RenderViewHost* render_view_host) OVERRIDE;
     46   virtual void NavigationStopped() OVERRIDE;
     47 
     48   // Update the thumbnail of the given tab contents if necessary.
     49   void UpdateThumbnailIfNecessary(content::WebContents* web_contents);
     50 
     51   // Called when a render view host was created for a WebContents.
     52   void RenderViewHostCreated(content::RenderViewHost* renderer);
     53 
     54   // Indicates that the given widget has changed is visibility.
     55   void WidgetHidden(content::RenderWidgetHost* widget);
     56 
     57   bool enabled_;
     58 
     59   content::NotificationRegistrar registrar_;
     60 
     61   bool load_interrupted_;
     62 
     63   DISALLOW_COPY_AND_ASSIGN(ThumbnailTabHelper);
     64 };
     65 
     66 #endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAIL_TAB_HELPER_H_
     67