Make RendererGpuVideoDecoderFactories live on arbitrary threads.

media/filters/gpu_video_decoder.h

Index: media/filters/gpu_video_decoder.h
diff --git a/media/filters/gpu_video_decoder.h b/media/filters/gpu_video_decoder.h
index f7e3f8f17b560b4d256e9eb7cc05c8818c0304cd..b65828fbc9a0715ea9f54805e0165ba977802945 100644
--- a/media/filters/gpu_video_decoder.h
+++ b/media/filters/gpu_video_decoder.h
@@ -28,17 +28,17 @@ class SkBitmap;
 namespace media {
 
 class DecoderBuffer;
-class VDAClientProxy;
 
 // GPU-accelerated video decoder implementation.  Relies on
 // AcceleratedVideoDecoderMsg_Decode and friends.
-// All methods internally trampoline to the |message_loop| passed to the ctor.
 class MEDIA_EXPORT GpuVideoDecoder
     : public VideoDecoder,
       public VideoDecodeAccelerator::Client {
  public:
   // Helper interface for specifying factories needed to instantiate a
   // GpuVideoDecoder.
+  // TODO(wuchengli): move this out of GpuVideoDecoder because RTCVideoDecoder

[Ami GONE FROM CHROMIUM, 2013/07/22 19:46:21]

Rebase makes this unnecessary?

[wuchengli, 2013/07/23 16:29:28]

I couldn't submit that CL today because of submit try bots failures. Some other
people were blocked by the same failure. I'll rebase my CL as soon as it is
submitted.

+  // also uses this.
   class MEDIA_EXPORT Factories : public base::RefCountedThreadSafe<Factories> {
    public:
     // Caller owns returned pointer.
@@ -72,11 +72,15 @@ class MEDIA_EXPORT GpuVideoDecoder
     // Returns true if Abort() has been called.
     virtual bool IsAborted() = 0;
 
+    // Makes a copy of |this|.
+    virtual scoped_refptr<Factories> Clone() = 0;
+
    protected:
     friend class base::RefCountedThreadSafe<Factories>;
     virtual ~Factories();
   };
 
+  // |message_loop| should be the same as the one running |factories|.

[Ami GONE FROM CHROMIUM, 2013/07/22 19:46:21]

Why not drop this param and just use factories->GetMessageLoop().get() instead?

[wuchengli, 2013/07/23 16:29:28]

That was recommended by Andrew.
https://codereview.chromium.org/19534002/diff/2002/media/filters/gpu_video_de...

Andrew. I've changed this back. First I feel using the message loop of
|factories| is natural because it is the "factory" of the video decoder. Also we
can remove DCHECKs and the lines of code are less. Second those
DCHECK(gvd_loop_proxy_->BelongsToCurrentThread()) in GpuVideoDecoder methods
will still require |factories| must have been created to work on the media
message loop.

   GpuVideoDecoder(const scoped_refptr<base::MessageLoopProxy>& message_loop,
                   const scoped_refptr<Factories>& factories);
 
@@ -133,13 +137,6 @@ class MEDIA_EXPORT GpuVideoDecoder
   void GetBufferData(int32 id, base::TimeDelta* timetamp,
                      gfx::Rect* visible_rect, gfx::Size* natural_size);
 
-  // Sets |vda_| and |weak_vda_| on the GVD thread and runs |status_cb|.
-  void SetVDA(const PipelineStatusCB& status_cb,
-              VideoDecodeAccelerator* vda,
-              base::WeakPtr<VideoDecodeAccelerator> weak_vda);
-
-  // Call VDA::Destroy() on |vda_loop_proxy_| ensuring that |this| outlives the
-  // Destroy() call.
   void DestroyVDA();
 
   // A shared memory segment and its allocated size.
@@ -161,28 +158,16 @@ class MEDIA_EXPORT GpuVideoDecoder
 
   bool needs_bitstream_conversion_;
 
-  // Message loop on which to fire callbacks and trampoline calls to this class
-  // if they arrive on other loops.
+  // Message loop which this class and |factories_| run on.
   scoped_refptr<base::MessageLoopProxy> gvd_loop_proxy_;
   base::WeakPtrFactory<GpuVideoDecoder> weak_factory_;
   base::WeakPtr<GpuVideoDecoder> weak_this_;
 
-  // Message loop on which to makes all calls to vda_.  (beware this loop may be
-  // paused during the Pause/Flush/Stop dance PipelineImpl::Stop() goes
-  // through).
-  scoped_refptr<base::MessageLoopProxy> vda_loop_proxy_;
-
   scoped_refptr<Factories> factories_;
 
-  // Proxies calls from |vda_| to |gvd_loop_proxy_| and used to safely detach
-  // during shutdown.
-  scoped_refptr<VDAClientProxy> client_proxy_;
-
-  // Populated during Initialize() via SetVDA() (on success) and unchanged
-  // until an error occurs.
+  // Populated during Initialize() (on success) and unchanged until an error
+  // occurs.
   scoped_ptr<VideoDecodeAccelerator> vda_;
-  // Used to post tasks from the GVD thread to the VDA thread safely.
-  base::WeakPtr<VideoDecodeAccelerator> weak_vda_;
 
   // Callbacks that are !is_null() only during their respective operation being
   // asynchronously executed.