Implement lifetime observer on RenderWidgetHostViewBase.

content/browser/renderer_host/render_widget_host_view_base.h

 // 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 CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "base/process/kill.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "cc/output/compositor_frame.h"
 #include "content/browser/renderer_host/event_with_latency_info.h"
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "content/public/browser/readback_types.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "ipc/ipc_listener.h"
@@ skipping 28 matching lines @@
 class SurfaceHittestDelegate;
 }
 
 namespace ui {
 class LatencyInfo;
 }
 
 namespace content {
 class BrowserAccessibilityDelegate;
 class BrowserAccessibilityManager;
+class RenderWidgetHostViewBaseObserver;
 class SyntheticGesture;
 class SyntheticGestureTarget;
 class WebCursor;
 struct DidOverscrollParams;
 struct NativeWebKeyboardEvent;
 struct WebPluginGeometry;
 
 // Basic implementation shared by concrete RenderWidgetHostView subclasses.
 class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
                                                 public IPC::Listener {
@@ skipping 306 matching lines @@
 
   // Returns an HWND that's given as the parent window for windowless Flash to
   // workaround crbug.com/301548.
   virtual gfx::NativeViewId GetParentForWindowlessPlugin() const = 0;
 
   // The callback that DetachPluginsHelper calls for each child window. Call
   // this directly if you want to do custom filtering on plugin windows first.
   static void DetachPluginWindowsCallback(HWND window);
 #endif
 
+  // Add and remove observers for lifetime event notifications. The order in
+  // which notifications are sent to observers is undefined. Clients must be
+  // sure to remove the observer before they go away.
+  void AddObserver(RenderWidgetHostViewBaseObserver* observer);
+  void RemoveObserver(RenderWidgetHostViewBaseObserver* observer);
+
  protected:
   // Interface class only, do not construct.
   RenderWidgetHostViewBase();
 
+  void NotifyObserversAboutShutdown();
+
 #if defined(OS_WIN)
   // Shared implementation of MovePluginWindows for use by win and aura/wina.
   static void MovePluginWindowsHelper(
       HWND parent,
       const std::vector<WebPluginGeometry>& moves);
 
   static void PaintPluginWindowsHelper(
       HWND parent,
       const gfx::Rect& damaged_screen_rect);
 
@@ skipping 42 matching lines @@
 
  private:
   void FlushInput();
 
   gfx::Rect current_display_area_;
 
   uint32_t renderer_frame_number_;
 
   base::OneShotTimer flush_input_timer_;
 
+  base::ObserverList<RenderWidgetHostViewBaseObserver> observers_;
+
   base::WeakPtrFactory<RenderWidgetHostViewBase> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewBase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_