Refactor RenderWidgetHost::set_paint_observer()

chrome/browser/tab_contents/thumbnail_generator.h

 // Copyright (c) 2010 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_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_
 #define CHROME_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_
 #pragma once
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/linked_ptr.h"
 #include "base/lock.h"
 #include "base/timer.h"
-#include "chrome/browser/renderer_host/render_widget_host_painting_observer.h"
+#include "chrome/browser/renderer_host/backing_store.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
 
 class RenderWidgetHost;
 class SkBitmap;
 class TabContents;
 
-// This class MUST be destroyed after the RenderWidgetHosts, since it installs
-// a painting observer that is not removed.
-class ThumbnailGenerator : public RenderWidgetHostPaintingObserver,
-                           public NotificationObserver {
+class ThumbnailGenerator : NotificationObserver {
  public:
   typedef Callback1<const SkBitmap&>::Type ThumbnailReadyCallback;
   // This class will do nothing until you call StartThumbnailing.
   ThumbnailGenerator();
   ~ThumbnailGenerator();
 
   // Ensures that we're properly hooked in to generated thumbnails. This can
   // be called repeatedly and with wild abandon to no ill effect.
   void StartThumbnailing();
 
@@ skipping 17 matching lines @@
   void AskForSnapshot(RenderWidgetHost* renderer,
                       bool prefer_backing_store,
                       ThumbnailReadyCallback* callback,
                       gfx::Size page_size,
                       gfx::Size desired_size);
 
   // This returns a thumbnail of a fixed, small size for the given
   // renderer.
   SkBitmap GetThumbnailForRenderer(RenderWidgetHost* renderer) const;
 
+  // Start or stop monitoring notifications for |renderer| based on the value
+  // of |monitor|.
+  void MonitorRenderer(RenderWidgetHost* renderer, bool monitor);
+
 #ifdef UNIT_TEST
   // When true, the class will not use a timeout to do the expiration. This
   // will cause expiration to happen on the next run of the message loop.
   // Unit tests case use this to test expiration by choosing when the message
   // loop runs.
   void set_no_timeout(bool no_timeout) { no_timeout_ = no_timeout; }
 #endif
 
  private:
   // RenderWidgetHostPaintingObserver implementation.
@@ skipping 44 matching lines @@
   // Map of callback objects by sequence number.
   struct AsyncRequestInfo;
   typedef std::map<int,
                    linked_ptr<AsyncRequestInfo> > ThumbnailCallbackMap;
   ThumbnailCallbackMap callback_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ThumbnailGenerator);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_