text: // 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_THUMBNAILS_THUMBNAIL_TAB_HELPER_H_
  #define CHROME_BROWSER_THUMBNAILS_THUMBNAIL_TAB_HELPER_H_
  
  #include "base/macros.h"
  #include "base/memory/weak_ptr.h"
  #include "chrome/browser/thumbnails/thumbnailing_context.h"
  #include "content/public/browser/notification_observer.h"
  #include "content/public/browser/notification_registrar.h"
  #include "content/public/browser/readback_types.h"
  #include "content/public/browser/web_contents_observer.h"
  #include "content/public/browser/web_contents_user_data.h"
  
  namespace content {
  class RenderViewHost;
  class RenderWidgetHost;
  }
  
  class ThumbnailTabHelper
      : public content::NotificationObserver,
        public content::WebContentsObserver,
        public content::WebContentsUserData<ThumbnailTabHelper> {
   public:
    ~ThumbnailTabHelper() override;
  
   private:
    explicit ThumbnailTabHelper(content::WebContents* contents);
    friend class content::WebContentsUserData<ThumbnailTabHelper>;
  
    // content::NotificationObserver overrides.
    void Observe(int type,
                 const content::NotificationSource& source,
                 const content::NotificationDetails& details) override;
  
    // content::WebContentsObserver overrides.
    void RenderViewDeleted(content::RenderViewHost* render_view_host) override;
    void DidStartLoading() override;
    void NavigationStopped() override;
  
    // Update the thumbnail of the given tab contents if necessary.
    void UpdateThumbnailIfNecessary();
  
    // Initiate asynchronous generation of a thumbnail from the web contents.
    void AsyncProcessThumbnail(
        scoped_refptr<thumbnails::ThumbnailService> thumbnail_service);
  
    // Create a thumbnail from the web contents bitmap.
    void ProcessCapturedBitmap(
        scoped_refptr<thumbnails::ThumbnailingAlgorithm> algorithm,
        const SkBitmap& bitmap,
        content::ReadbackResponse response);
  
    // Pass the thumbnail to the thumbnail service.
    void UpdateThumbnail(
        const thumbnails::ThumbnailingContext& context,
        const SkBitmap& thumbnail);
  
    // Clean up after thumbnail generation has ended.
    void CleanUpFromThumbnailGeneration();
  
    // Called when a render view host was created for a WebContents.
    void RenderViewHostCreated(content::RenderViewHost* renderer);
  
    // Indicates that the given widget has changed is visibility.
    void WidgetHidden(content::RenderWidgetHost* widget);
  
    content::NotificationRegistrar registrar_;
    scoped_refptr<thumbnails::ThumbnailingContext> thumbnailing_context_;
  
    bool load_interrupted_;
  
    base::WeakPtrFactory<ThumbnailTabHelper> weak_factory_;
  
    DISALLOW_COPY_AND_ASSIGN(ThumbnailTabHelper);
  };
  
  #endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAIL_TAB_HELPER_H_
  