Make RendererGpuVideoDecoderFactories live on arbitrary threads.

content/renderer/media/rtc_video_decoder_factory.h

Index: content/renderer/media/rtc_video_decoder_factory.h
diff --git a/content/renderer/media/rtc_video_decoder_factory.h b/content/renderer/media/rtc_video_decoder_factory.h
index 1974701cf58867fdea5b5cd98af8addbd29c9700..27d219e0dae0496b1a58eecb31c739e9b21f5f9d 100644
--- a/content/renderer/media/rtc_video_decoder_factory.h
+++ b/content/renderer/media/rtc_video_decoder_factory.h
@@ -22,6 +22,7 @@ class CONTENT_EXPORT RTCVideoDecoderFactory
     : NON_EXPORTED_BASE(public cricket::WebRtcVideoDecoderFactory) {
  public:
   RTCVideoDecoderFactory(
+      const scoped_refptr<base::MessageLoopProxy>& vda_loop_proxy,
       const scoped_refptr<media::GpuVideoDecoder::Factories>& gpu_factories);
   virtual ~RTCVideoDecoderFactory();
 
@@ -36,7 +37,7 @@ class CONTENT_EXPORT RTCVideoDecoderFactory
 
  private:
   scoped_refptr<base::MessageLoopProxy> vda_loop_proxy_;
-  scoped_ptr<webrtc::VideoDecoder> decoder_;
+  scoped_refptr<media::GpuVideoDecoder::Factories> gpu_factories_;
 
   DISALLOW_COPY_AND_ASSIGN(RTCVideoDecoderFactory);
 };