We have a problem in the process on destroying WebContentsImpl because

content/browser/media/capture/web_contents_video_capture_device.cc

 // 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.
 //
 // Implementation notes: This needs to work on a variety of hardware
 // configurations where the speed of the CPU and GPU greatly affect overall
 // performance. Spanning several threads, the process of capturing has been
 // split up into four conceptual stages:
 //
 //   1. Reserve Buffer: Before a frame can be captured, a slot in the client's
@@ skipping 260 matching lines @@
   virtual void AboutToNavigateRenderView(RenderViewHost* rvh) OVERRIDE {
     RenewFrameSubscription();
   }
 
   virtual void DidNavigateMainFrame(
       const LoadCommittedDetails& details,
       const FrameNavigateParams& params) OVERRIDE {
     RenewFrameSubscription();
   }
 
-  virtual void WebContentsDestroyed(WebContents* web_contents) OVERRIDE;
+  virtual void WebContentsDestroyed() OVERRIDE;
 
  private:
   // Starts observing the web contents, returning false if lookup fails.
   bool StartObservingWebContents();
 
   // Helper function to determine the view that we are currently tracking.
   RenderWidgetHost* GetTarget();
 
   // Response callback for RenderWidgetHost::CopyFromBackingStore().
   void DidCopyFromBackingStore(
@@ skipping 406 matching lines @@
     contents->IncrementCapturerCount(oracle_proxy_->GetCaptureSize());
     fullscreen_widget_id_ = contents->GetFullscreenWidgetRoutingID();
     RenewFrameSubscription();
     return true;
   }
 
   DVLOG(1) << "WebContents::FromRenderViewHost(" << rvh << ") returned NULL.";
   return false;
 }
 
-void WebContentsCaptureMachine::WebContentsDestroyed(
-    WebContents* web_contents) {
+void WebContentsCaptureMachine::WebContentsDestroyed() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   subscription_.reset();
-  web_contents->DecrementCapturerCount();
+  web_contents()->DecrementCapturerCount();
   oracle_proxy_->ReportError("WebContentsDestroyed()");
 }
 
 RenderWidgetHost* WebContentsCaptureMachine::GetTarget() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (!web_contents())
     return NULL;
 
   RenderWidgetHost* rwh = NULL;
   if (fullscreen_widget_id_ != MSG_ROUTING_NONE) {
@@ skipping 94 matching lines @@
     scoped_ptr<Client> client) {
   DVLOG(1) << "Allocating " << params.requested_format.frame_size.ToString();
   core_->AllocateAndStart(params, client.Pass());
 }
 
 void WebContentsVideoCaptureDevice::StopAndDeAllocate() {
   core_->StopAndDeAllocate();
 }
 
 }  // namespace content