Fix crashes in ui::Compositor on Mac.

content/browser/renderer_host/render_widget_host_view_mac.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_MAC_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 #include <IOSurface/IOSurfaceAPI.h>
 #include <list>
@@ skipping 533 matching lines @@
   scoped_ptr<PendingSwapAck> pending_swap_ack_;
   void AddPendingSwapAck(int32 route_id, int gpu_host_id, int32 renderer_id);
 
   // Returns whether this render view is a popup (autocomplete window).
   bool IsPopup() const;
 
   // Shuts down the render_widget_host_.  This is a separate function so we can
   // invoke it from the message loop.
   void ShutdownHost();
 
+  // Tear down all components of the browser compositor in an order that will
+  // ensure no dangling references.
+  void ShutdownBrowserCompositor();
+
   void EnsureBrowserCompositorView();
   void DestroyBrowserCompositorView();
 
   void EnsureSoftwareLayer();
   void DestroySoftwareLayer();
 
   bool EnsureCompositedIOSurface() WARN_UNUSED_RESULT;
   void EnsureCompositedIOSurfaceLayer();
   enum DestroyCompositedIOSurfaceLayerBehavior {
     kLeaveLayerInHierarchy,
@@ skipping 70 matching lines @@
   scoped_ptr<RenderWidgetHostViewFrameSubscriber> frame_subscriber_;
 
   base::WeakPtrFactory<RenderWidgetHostViewMac>
       software_frame_weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewMac);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_