Implement actually decoding frames in VTVideoDecodeAccelerator.

content/common/gpu/media/vt_video_decode_accelerator.h

Index: content/common/gpu/media/vt_video_decode_accelerator.h
diff --git a/content/common/gpu/media/vt_video_decode_accelerator.h b/content/common/gpu/media/vt_video_decode_accelerator.h
index 08dd8ab8454ca08a1b6fbaa48133643087aa874e..e278b3c53c3c48a968ece02c52a33b4c5f9839c6 100644
--- a/content/common/gpu/media/vt_video_decode_accelerator.h
+++ b/content/common/gpu/media/vt_video_decode_accelerator.h
@@ -5,7 +5,11 @@
 #ifndef CONTENT_COMMON_GPU_MEDIA_VT_VIDEO_DECODE_ACCELERATOR_H_
 #define CONTENT_COMMON_GPU_MEDIA_VT_VIDEO_DECODE_ACCELERATOR_H_
 
-#include "base/basictypes.h"
+#include <stdint.h>
+
+#include <map>
+#include <queue>
+
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
@@ -45,38 +49,74 @@ class VTVideoDecodeAccelerator
   virtual void Destroy() OVERRIDE;
   virtual bool CanDecodeOnIOThread() OVERRIDE;
 
-  // Called by VideoToolbox when a frame is decoded.
+  // Called by OutputThunk() when VideoToolbox finishes decoding a frame.
   void Output(
       int32_t bitstream_id,
       OSStatus status,
-      VTDecodeInfoFlags info_flags,
       CVImageBufferRef image_buffer);
 
  private:
-  // Configure a VideoToolbox decompression session from parameter set NALUs.
+  struct DecodedFrame {
+    DecodedFrame(uint32_t bitstream_id, CVImageBufferRef image_buffer);

[Pawel Osciak, 2014/08/02 00:28:15]

s/uint32_t/int32_t/

[sandersd (OOO until July 31), 2014/08/04 19:24:20]

Done.

+    ~DecodedFrame();
+
+    int32_t bitstream_id;
+    base::ScopedCFTypeRef<CVImageBufferRef> image_buffer;
+  };
+
+  // Methods for interacting with VideoToolbox. Run on |decoder_thread_|.
   void ConfigureDecoder(
       const std::vector<const uint8_t*>& nalu_data_ptrs,
       const std::vector<size_t>& nalu_data_sizes);
-
-  // Decode a frame of bitstream.
   void DecodeTask(const media::BitstreamBuffer);
 
+  // Methods for interacting with |client_|. Run on |gpu_task_runner_|.
+  void OutputTask(DecodedFrame frame);
+  void SizeChangedTask(gfx::Size coded_size);
+  void SendPictures();
+
+  //
+  // GPU thread state.
+  //
   CGLContextObj cgl_context_;
   media::VideoDecodeAccelerator::Client* client_;
-  base::Thread decoder_thread_;
+  gfx::Size texture_size_;
 
-  // Decoder configuration (used only on decoder thread).
+  // Texture IDs of pictures.
+  // TODO(sandersd): A single map of structs holding picture data.
+  std::map<int32_t, uint32_t> texture_ids_;
+
+  // Pictures ready to be rendered to.
+  std::queue<int32_t> available_picture_ids_;
+
+  // Decoded frames ready to render.
+  std::queue<DecodedFrame> decoded_frames_;
+
+  // Image buffers retained while they are bound to pictures.

[Pawel Osciak, 2014/08/02 00:28:15]

Nit: I'd explain this is used to keep a ref to CVImageBuffer while at display.
Right?

[sandersd (OOO until July 31), 2014/08/04 19:24:20]

I was using the word 'retained' to mean that precisely. I've reworded it to use
more generic terms.

+  std::map<int32_t, base::ScopedCFTypeRef<CVImageBufferRef>> picture_bindings_;
+
+  //
+  // Decoder thread state.
+  //
   VTDecompressionOutputCallbackRecord callback_;
   base::ScopedCFTypeRef<CMFormatDescriptionRef> format_;
   base::ScopedCFTypeRef<VTDecompressionSessionRef> session_;
   media::H264Parser parser_;
   gfx::Size coded_size_;
 
-  // Member variables should appear before the WeakPtrFactory, to ensure
-  // that any WeakPtrs to Controller are invalidated before its members
-  // variable's destructors are executed, rendering them invalid.
+  //
+  // Unprotected shared state (set up and torn down on GPU thread).
+  //
+  scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner_;
+
+  // This WeakPtrFactory does not need to be last as its pointers are bound to
+  // the same thread it is destructed on (the GPU thread).
   base::WeakPtrFactory<VTVideoDecodeAccelerator> weak_this_factory_;
 
+  // Declared last to ensure that all decoder thread tasks complete before any
+  // state is destructed.
+  base::Thread decoder_thread_;
+
   DISALLOW_COPY_AND_ASSIGN(VTVideoDecodeAccelerator);
 };