Remove MediaStreamDeviceThread in favor of audio worker TaskRunner.

content/browser/renderer_host/media/media_stream_provider.h

Index: content/browser/renderer_host/media/media_stream_provider.h
diff --git a/content/browser/renderer_host/media/media_stream_provider.h b/content/browser/renderer_host/media/media_stream_provider.h
index 051bb2ce294a69389b7ae0b7aa9f1a4d04e0825f..f83aa4f1ec281bb6a17bfbe5d4020d4c5aec865c 100644
--- a/content/browser/renderer_host/media/media_stream_provider.h
+++ b/content/browser/renderer_host/media/media_stream_provider.h
@@ -20,7 +20,7 @@
 #include "content/common/media/media_stream_options.h"
 
 namespace base {
-class MessageLoopProxy;
+class SingleThreadTaskRunner;
 }
 
 namespace content {
@@ -60,7 +60,8 @@ class CONTENT_EXPORT MediaStreamProvider
  public:
   // Registers a listener and a device message loop.
   virtual void Register(MediaStreamProviderListener* listener,
-                        base::MessageLoopProxy* device_thread_loop) = 0;
+                        const scoped_refptr<base::SingleThreadTaskRunner>&
+                            device_task_runner) = 0;
 
   // Unregisters the previously registered listener.
   virtual void Unregister() = 0;