Add missed NULL check in r274802

content/browser/renderer_host/render_widget_host_view_mac.mm

 // 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.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <QuartzCore/QuartzCore.h>
 
 #include "base/basictypes.h"
@@ skipping 2317 matching lines @@
 // BrowserCompositorViewMacClient, public:
 
 void RenderWidgetHostViewMac::BrowserCompositorDidDrawFrame() {
   PostReleaseBrowserCompositorLock();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // CompositingIOSurfaceLayerClient, public:
 
 void RenderWidgetHostViewMac::AcceleratedLayerDidDrawFrame(bool succeeded) {
+  if (!render_widget_host_)
+    return;
+
   SendPendingLatencyInfoToHost();
   SendPendingSwapAck();
   if (!succeeded)
     GotAcceleratedCompositingError();
 }
 
 }  // namespace content
 
 // RenderWidgetHostViewCocoa ---------------------------------------------------
 
@@ skipping 1684 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end