Clarify ownership of GpuVideoDecodeAcceleratorHost and avoid crash on context loss.

content/common/gpu/client/gpu_video_decode_accelerator_host.h

 // Copyright (c) 2012 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_COMMON_GPU_CLIENT_GPU_VIDEO_DECODE_ACCELERATOR_HOST_H_
 #define CONTENT_COMMON_GPU_CLIENT_GPU_VIDEO_DECODE_ACCELERATOR_HOST_H_
 
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "ipc/ipc_listener.h"
 #include "media/video/video_decode_accelerator.h"
 
 class GpuChannelHost;
 
 // This class is used to talk to VideoDecodeAccelerator in the Gpu process
 // through IPC messages.
 class GpuVideoDecodeAcceleratorHost
     : public IPC::Listener,
       public media::VideoDecodeAccelerator,
       public base::NonThreadSafe {
  public:
   // |channel| is used to send IPC messages to GPU process.
   GpuVideoDecodeAcceleratorHost(GpuChannelHost* channel,
                                 int32 decoder_route_id,
                                 media::VideoDecodeAccelerator::Client* client);
-  virtual ~GpuVideoDecodeAcceleratorHost();
 
   // IPC::Listener implementation.
   virtual void OnChannelError() OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
   // media::VideoDecodeAccelerator implementation.
   virtual bool Initialize(media::VideoCodecProfile profile) 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:
+  // Only Destroy() should be deleting |this|.
+  virtual ~GpuVideoDecodeAcceleratorHost();
+
   void Send(IPC::Message* message);
 
   void OnBitstreamBufferProcessed(int32 bitstream_buffer_id);
   void OnProvidePictureBuffer(uint32 num_requested_buffers,
                               const gfx::Size& buffer_size,
                               uint32 texture_target);
   void OnDismissPictureBuffer(int32 picture_buffer_id);
   void OnPictureReady(int32 picture_buffer_id, int32 bitstream_buffer_id);
   void OnFlushDone();
   void OnResetDone();
   void OnErrorNotification(uint32 error);
 
   // Sends IPC messages to the Gpu process.
   GpuChannelHost* channel_;
 
   // Route ID for the associated decoder in the GPU process.
   // TODO(fischman): storing route_id's for GPU process entities in the client
   // process is vulnerable to GPU process crashing & being respawned, and
   // attempting to use an outdated or reused route id.
   int32 decoder_route_id_;
 
   // Reference to the client that will receive callbacks from the decoder.
   media::VideoDecodeAccelerator::Client* client_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuVideoDecodeAcceleratorHost);
 };
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_GPU_VIDEO_DECODE_ACCELERATOR_HOST_H_