Move the device enumerate/open/close work to device thread from IO thread

content/browser/renderer_host/media/video_capture_host.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_host.h"
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 #include "content/common/media/video_capture_messages.h"
 
 using content::BrowserMessageFilter;
 using content::BrowserThread;
 
 struct VideoCaptureHost::Entry {
   Entry(VideoCaptureController* controller)
       : controller(controller) {}
 
   ~Entry() {}
 
   scoped_refptr<VideoCaptureController> controller;
 };
 
-VideoCaptureHost::VideoCaptureHost(content::ResourceContext* resource_context,
-                                   media::AudioManager* audio_manager)
-    : resource_context_(resource_context),
-      audio_manager_(audio_manager) {
+VideoCaptureHost::VideoCaptureHost(content::ResourceContext* resource_context)
+    : resource_context_(resource_context) {
 }
 
 VideoCaptureHost::~VideoCaptureHost() {}
 
 void VideoCaptureHost::OnChannelClosing() {
   BrowserMessageFilter::OnChannelClosing();
 
   // Since the IPC channel is gone, close all requested VideCaptureDevices.
   for (EntryMap::iterator it = entries_.begin(); it != entries_.end(); it++) {
     VideoCaptureController* controller = it->second->controller;
@@ skipping 235 matching lines @@
     controller->StopCapture(controller_id, this);
     GetVideoCaptureManager()->RemoveController(controller, this);
   }
   delete it->second;
   entries_.erase(controller_id);
 }
 
 media_stream::VideoCaptureManager* VideoCaptureHost::GetVideoCaptureManager() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return media_stream::MediaStreamManager::GetForResourceContext(
-      resource_context_, audio_manager_)->video_capture_manager();
+      resource_context_)->video_capture_manager();
 }