Implement proper synchronization between HW video decode IPC and CommandBuffer.

content/common/gpu/media/gpu_video_decode_accelerator.h

Index: content/common/gpu/media/gpu_video_decode_accelerator.h
diff --git a/content/common/gpu/media/gpu_video_decode_accelerator.h b/content/common/gpu/media/gpu_video_decode_accelerator.h
index a7e5de33502e2ca235245e4357f08cef671d1311..e6671694d1146c3aa55ce70d1cbeed2bc56fb487 100644
--- a/content/common/gpu/media/gpu_video_decode_accelerator.h
+++ b/content/common/gpu/media/gpu_video_decode_accelerator.h
@@ -5,6 +5,7 @@
 #ifndef CONTENT_COMMON_GPU_MEDIA_GPU_VIDEO_DECODE_ACCELERATOR_H_
 #define CONTENT_COMMON_GPU_MEDIA_GPU_VIDEO_DECODE_ACCELERATOR_H_
 
+#include <queue>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
@@ -13,13 +14,18 @@
 #include "ipc/ipc_message.h"
 #include "media/video/video_decode_accelerator.h"
 
+class GpuCommandBufferStub;
+
 class GpuVideoDecodeAccelerator
     : public base::RefCountedThreadSafe<GpuVideoDecodeAccelerator>,
       public IPC::Channel::Listener,
       public IPC::Message::Sender,
       public media::VideoDecodeAccelerator::Client {
  public:
-  GpuVideoDecodeAccelerator(IPC::Message::Sender* sender, int32 host_route_id);
+  GpuVideoDecodeAccelerator(IPC::Message::Sender* sender,
+                            int32 host_route_id,
+                            int32 decoder_route_id,
+                            GpuCommandBufferStub* stub);
   virtual ~GpuVideoDecodeAccelerator();
 
   // IPC::Channel::Listener implementation.
@@ -52,24 +58,56 @@ class GpuVideoDecodeAccelerator
 
   void AssignGLESBuffers(const std::vector<media::GLESBuffer>& buffers);
 
+  // Callback to be fired when the underlying stub receives a new token.
+  void OnSetToken(int32 token);
+
  private:
+  // Defers |msg| for later processing if it specifies a write token that hasn't
+  // come to pass yet, and set |*deferred| to true.  Return false if the message
+  // failed to parse.
+  bool DeferMessageIfNeeded(const IPC::Message& msg, bool* deferred);
+
   // Handlers for IPC messages.
-  void OnGetConfigs(const std::vector<uint32>& config,
-                    std::vector<uint32>* configs);
-  void OnInitialize(const std::vector<uint32>& configs);
-  void OnDecode(int32 id, base::SharedMemoryHandle handle, int32 size);
-  void OnAssignSysmemBuffers(const std::vector<int32>& buffer_ids,
-                             const std::vector<base::SharedMemoryHandle>& data,
-                             const std::vector<gfx::Size>& sizes);
-  void OnReusePictureBuffer(int32 picture_buffer_id);
-  void OnFlush();
-  void OnAbort();
+  void OnGetConfigs(
+      const std::pair<int32, int32>& /* tokens */,
+      const std::vector<uint32>& config,
+      std::vector<uint32>* configs);
+  void OnInitialize(
+      const std::pair<int32, int32>& /* tokens */,
+      const std::vector<uint32>& configs);
+  void OnDecode(
+      const std::pair<int32, int32>& /* tokens */,
+      base::SharedMemoryHandle handle, int32 id, int32 size);
+  void OnAssignTextures(
+      const std::pair<int32, int32>& /* tokens */,
+      const std::vector<int32>& buffer_ids,
+      const std::vector<uint32>& texture_ids,
+      const std::vector<gfx::Size>& sizes);
+  void OnAssignSysmemBuffers(
+      const std::pair<int32, int32>& /* tokens */,
+      const std::vector<int32> buffer_ids,
+      const std::vector<base::SharedMemoryHandle> data,
+      const std::vector<gfx::Size> sizes);
+  void OnReusePictureBuffer(
+      const std::pair<int32, int32>& /* tokens */,
+      int32 picture_buffer_id);
+  void OnFlush(const std::pair<int32, int32>& /* tokens */);
+  void OnAbort(const std::pair<int32, int32>& /* tokens */);
 
   // Pointer to the IPC message sender.
   IPC::Message::Sender* sender_;
 
   // Route ID to communicate with the host.
-  int32 route_id_;
+  int32 host_route_id_;
+
+  // Route ID of the decoder.
+  int32 decoder_route_id_;
+
+  // Messages deferred for later processing when their tokens have come to pass.
+  std::queue<IPC::Message*> deferred_messages_;
+
+  // Unowned pointer to the underlying GpuCommandBufferStub.
+  GpuCommandBufferStub* stub_;
 
   // Pointer to the underlying VideoDecodeAccelerator.
   scoped_ptr<media::VideoDecodeAccelerator> video_decode_accelerator_;