Win Video Capture: Create an STA |video_capture_thread_| from MediaStreamManager.

content/browser/renderer_host/media/video_capture_manager.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.
 
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 114 matching lines @@
     const scoped_refptr<base::SingleThreadTaskRunner>& device_task_runner) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(!listener_);
   DCHECK(!device_task_runner_.get());
   listener_ = listener;
   device_task_runner_ = device_task_runner;
 }
 
 void VideoCaptureManager::Unregister() {
   DCHECK(listener_);
+  DCHECK(device_task_runner_.get());
   listener_ = NULL;
+  device_task_runner_ = NULL;
 }
 
 void VideoCaptureManager::EnumerateDevices(MediaStreamType stream_type) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(1) << "VideoCaptureManager::EnumerateDevices, type " << stream_type;
   DCHECK(listener_);
   DCHECK_EQ(stream_type, MEDIA_DEVICE_VIDEO_CAPTURE);
 
   // Bind a callback to ConsolidateDevicesInfoOnDeviceThread() with an argument
   // for another callback to OnDevicesInfoEnumerated() to be run in the current
@@ skipping 574 matching lines @@
     gfx::NativeViewId window_id) {
   DCHECK(IsOnDeviceThread());
   DCHECK(notification_window_ids_.find(session_id) ==
          notification_window_ids_.end());
   notification_window_ids_[session_id] = window_id;
   VLOG(2) << "Screen capture notification window saved for session "
           << session_id << " on device thread.";
 }
 
 }  // namespace content