Revert of Revert of Implement software fallback for PPB_VideoDecoder.

content/renderer/pepper/video_decoder_shim.h

Index: content/renderer/pepper/video_decoder_shim.h
diff --git a/content/renderer/pepper/video_decoder_shim.h b/content/renderer/pepper/video_decoder_shim.h
new file mode 100644
index 0000000000000000000000000000000000000000..e02af527bbaf0d41ba9cdbfac93d07eb448d2b72
--- /dev/null
+++ b/content/renderer/pepper/video_decoder_shim.h
@@ -0,0 +1,129 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_RENDERER_PEPPER_VIDEO_DECODER_SHIM_H_
+#define CONTENT_RENDERER_PEPPER_VIDEO_DECODER_SHIM_H_
+
+#include <queue>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/containers/hash_tables.h"
+#include "base/memory/linked_ptr.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "gpu/command_buffer/common/mailbox.h"
+#include "media/base/video_decoder_config.h"
+#include "media/video/video_decode_accelerator.h"
+
+#include "ppapi/c/pp_codecs.h"
+
+namespace gpu {
+namespace gles2 {
+class GLES2Interface;
+}
+}
+
+namespace media {
+class DecoderBuffer;
+}
+
+namespace webkit {
+namespace gpu {
+class ContextProviderWebContext;
+}
+}
+
+namespace content {
+
+class PepperVideoDecoderHost;
+
+// This class is a shim to wrap a media::VideoDecoder so that it can be used
+// by PepperVideoDecoderHost in place of a media::VideoDecodeAccelerator.
+// This class should be constructed, used, and destructed on the main (render)
+// thread.
+class VideoDecoderShim : public media::VideoDecodeAccelerator {
+ public:
+  explicit VideoDecoderShim(PepperVideoDecoderHost* host);
+  virtual ~VideoDecoderShim();
+
+  // media::VideoDecodeAccelerator implementation.
+  virtual bool Initialize(
+      media::VideoCodecProfile profile,
+      media::VideoDecodeAccelerator::Client* client) OVERRIDE;
+  virtual void Decode(const media::BitstreamBuffer& bitstream_buffer) OVERRIDE;
+  virtual void AssignPictureBuffers(
+      const std::vector<media::PictureBuffer>& buffers) OVERRIDE;
+  virtual void ReusePictureBuffer(int32 picture_buffer_id) OVERRIDE;
+  virtual void Flush() OVERRIDE;
+  virtual void Reset() OVERRIDE;
+  virtual void Destroy() OVERRIDE;
+
+ private:
+  enum State {
+    UNINITIALIZED,
+    DECODING,
+    FLUSHING,
+    RESETTING,
+  };
+
+  struct PendingDecode;
+  struct PendingFrame;
+  class DecoderImpl;
+
+  void OnInitializeComplete(int32_t result, uint32_t texture_pool_size);
+  void OnDecodeComplete(int32_t result, uint32_t decode_id);
+  void OnOutputComplete(scoped_ptr<PendingFrame> frame);
+  void SendPictures();
+  void OnResetComplete();
+  void NotifyCompletedDecodes();
+  void DismissTexture(uint32_t texture_id);
+  void DeleteTexture(uint32_t texture_id);
+  // Call this whenever we change GL state that the plugin relies on, such as
+  // creating picture textures.
+  void FlushCommandBuffer();
+
+  scoped_ptr<DecoderImpl> decoder_impl_;
+  State state_;
+
+  PepperVideoDecoderHost* host_;
+  scoped_refptr<base::MessageLoopProxy> media_message_loop_;
+  scoped_refptr<webkit::gpu::ContextProviderWebContext> context_provider_;
+
+  // The current decoded frame size.
+  gfx::Size texture_size_;
+  // Map that takes the plugin's GL texture id to the renderer's GL texture id.
+  typedef base::hash_map<uint32_t, uint32_t> TextureIdMap;
+  TextureIdMap texture_id_map_;
+  // Available textures (these are plugin ids.)
+  std::vector<uint32_t> available_textures_;
+  // Track textures that are no longer needed (these are plugin ids.)
+  typedef base::hash_set<uint32_t> TextureIdSet;
+  TextureIdSet textures_to_dismiss_;
+  // Mailboxes for pending texture requests, to write to plugin's textures.
+  std::vector<gpu::Mailbox> pending_texture_mailboxes_;
+
+  // Queue of completed decode ids, for notifying the host.
+  typedef std::queue<uint32_t> CompletedDecodeQueue;
+  CompletedDecodeQueue completed_decodes_;
+
+  // Queue of decoded frames that have been converted to RGB and await upload to
+  // a GL texture.
+  typedef std::queue<linked_ptr<PendingFrame> > PendingFrameQueue;
+  PendingFrameQueue pending_frames_;
+
+  // The optimal number of textures to allocate for decoder_impl_.
+  uint32_t texture_pool_size_;
+
+  uint32_t num_pending_decodes_;
+
+  base::WeakPtrFactory<VideoDecoderShim> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoDecoderShim);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_PEPPER_VIDEO_DECODER_SHIM_H_