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

content/browser/renderer_host/media/video_capture_host.cc

Index: content/browser/renderer_host/media/video_capture_host.cc
diff --git a/content/browser/renderer_host/media/video_capture_host.cc b/content/browser/renderer_host/media/video_capture_host.cc
index 97da80d829bbe2d4c2ef7d544ca62d3960376bca..2d23060b2d22720cdf23ac3c7b24ce02461b2b1f 100644
--- a/content/browser/renderer_host/media/video_capture_host.cc
+++ b/content/browser/renderer_host/media/video_capture_host.cc
@@ -23,10 +23,8 @@ struct VideoCaptureHost::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() {}
@@ -282,5 +280,5 @@ void VideoCaptureHost::DeleteVideoCaptureControllerOnIOThread(
 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();
 }