Make RendererGpuVideoDecoderFactories live on arbitrary threads.

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index 561fcf6880bcf707801e1854e56bdbcfdecdbc66..13c4077844ff389b3e2545e05caa9d96dc80a420 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -19,8 +19,8 @@
 #include "content/common/gpu/client/gpu_channel_host.h"
 #include "content/common/gpu/gpu_process_launch_causes.h"
 #include "content/public/renderer/render_thread.h"
+#include "content/renderer/media/renderer_gpu_video_decoder_factories.h"
 #include "ipc/ipc_channel_proxy.h"
-#include "media/filters/gpu_video_decoder.h"
 #include "ui/gfx/native_widget_types.h"
 
 class GrContext;
@@ -254,9 +254,10 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
   // not sent for at least one notification delay.
   void PostponeIdleNotification();
 
-  // Gets gpu factories. Returns NULL if VDA is disabled or a graphics context
-  // cannot be obtained.
-  scoped_refptr<media::GpuVideoDecoder::Factories> GetGpuFactories();
+  // Gets gpu factories, which will run on |factories_loop|. Returns NULL if VDA
+  // is disabled or a graphics context cannot be obtained.
+  scoped_refptr<media::GpuVideoDecoder::Factories> GetGpuFactories(
+      const scoped_refptr<base::MessageLoopProxy>& factories_loop);
 
   // Returns a graphics context shared among all
   // RendererGpuVideoDecoderFactories, or NULL on error.  Context remains owned