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

content/browser/renderer_host/media/media_stream_dispatcher_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/media_stream_dispatcher_host.h"
 
 #include "content/common/media/media_stream_messages.h"
 #include "content/common/media/media_stream_options.h"
 #include "googleurl/src/gurl.h"
 
 using content::BrowserMessageFilter;
 using content::BrowserThread;
 
 namespace media_stream {
 
 struct MediaStreamDispatcherHost::StreamRequest {
   StreamRequest() : render_view_id(0), page_request_id(0) {}
   StreamRequest(int render_view_id, int page_request_id)
       : render_view_id(render_view_id),
         page_request_id(page_request_id ) {
   }
   int render_view_id;
   // Id of the request generated by MediaStreamDispatcher.
   int page_request_id;
 };
 
 MediaStreamDispatcherHost::MediaStreamDispatcherHost(
     content::ResourceContext* resource_context,
-    int render_process_id,
-    media::AudioManager* audio_manager)
+    int render_process_id)
     : resource_context_(resource_context),
-      render_process_id_(render_process_id),
-      audio_manager_(audio_manager) {
+      render_process_id_(render_process_id) {
 }
 
 void MediaStreamDispatcherHost::StreamGenerated(
     const std::string& label,
     const StreamDeviceInfoArray& audio_devices,
     const StreamDeviceInfoArray& video_devices) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DVLOG(1) << "MediaStreamDispatcherHost::StreamGenerated("
            << ", {label = " << label <<  "})";
 
@@ skipping 222 matching lines @@
            << security_origin.spec() << ")";
 
   std::string label;
   manager()->OpenDevice(this, render_process_id_, render_view_id,
                         device_id, type, security_origin, &label);
   DCHECK(!label.empty());
   streams_[label] = StreamRequest(render_view_id, page_request_id);
 }
 
 MediaStreamManager* MediaStreamDispatcherHost::manager() {
-  return MediaStreamManager::GetForResourceContext(
-      resource_context_, audio_manager_);
+  return MediaStreamManager::GetForResourceContext(resource_context_);
 }
 
 }  // namespace media_stream