[NotForReview] Convert accelerated JPEG Decoder IPC to Mojo

media/gpu/ipc/client/gpu_jpeg_decode_accelerator_host.h

Index: media/gpu/ipc/client/gpu_jpeg_decode_accelerator_host.h
diff --git a/media/gpu/ipc/client/gpu_jpeg_decode_accelerator_host.h b/media/gpu/ipc/client/gpu_jpeg_decode_accelerator_host.h
index 5dcefbfeb5490f57e2bbf785b9f92f6065006808..82004a8cfc1b82ee841341e65c0e213a8163d8d8 100644
--- a/media/gpu/ipc/client/gpu_jpeg_decode_accelerator_host.h
+++ b/media/gpu/ipc/client/gpu_jpeg_decode_accelerator_host.h
@@ -12,33 +12,23 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequence_checker.h"
+#include "media/gpu/mojo/jpeg_decoder.mojom.h"
 #include "media/video/jpeg_decode_accelerator.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
-namespace gpu {
-class GpuChannelHost;
-}
-
-namespace IPC {
-class Listener;
-class Message;
-}
-
 namespace media {
 
 // TODO(c.padhi): Move GpuJpegDecodeAcceleratorHost to media/gpu/mojo, see
 // http://crbug.com/699255.
 // This class is used to talk to JpegDecodeAccelerator in the GPU process
-// through IPC messages.
+// through Mojo messages.
 class GpuJpegDecodeAcceleratorHost : public JpegDecodeAccelerator {
  public:
   GpuJpegDecodeAcceleratorHost(
-      scoped_refptr<gpu::GpuChannelHost> channel,
-      int32_t route_id,
-      const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner);

[mcasas, 2017/06/06 00:20:48]

Don't name explicitly where a method is supposed to run:
name instead by its inteded usage, comment that this is 
usually the IO thread, and assert for its specific restrictions 
using, e.g.
https://cs.chromium.org/chromium/src/base/threading/thread_restrictions.cc?ty...

That'll simplify unit testing ;)

[Chandan, 2017/06/06 10:37:15]

Sure. But the name |io_task_runner| was already present. I did not rename it.
Also, GpuJpegDecodeAcceleratorHost does not run on IO. IO task runner is given
to GJDAH to ensure/check that it receives the ack IPC message on IO thread.

   ~GpuJpegDecodeAcceleratorHost() override;
 
   // JpegDecodeAccelerator implementation.
@@ -49,22 +39,16 @@ class GpuJpegDecodeAcceleratorHost : public JpegDecodeAccelerator {
               const scoped_refptr<VideoFrame>& video_frame) override;
   bool IsSupported() override;
 
-  base::WeakPtr<IPC::Listener> GetReceiver();
-
  private:
-  class Receiver;
-
-  void Send(IPC::Message* message);
-
-  scoped_refptr<gpu::GpuChannelHost> channel_;
-
-  // Route ID for the associated decoder in the GPU process.
-  int32_t decoder_route_id_;
+  void OnDecodeAck(int32_t bitstream_buffer_id, mojom::Error error);
+  void OnDecodeAckOnIOThread(int32_t bitstream_buffer_id, mojom::Error error);
 
   // GPU IO task runner.
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
-  std::unique_ptr<Receiver> receiver_;
+  Client* client_;
+
+  mojom::GpuJpegDecodeAcceleratorPtr jpeg_decoder_;
 
   SEQUENCE_CHECKER(sequence_checker_);