Adds locks for CommandBufferProxyImpl invalidation

media/gpu/ipc/client/gpu_video_encode_accelerator_host.h

 // Copyright 2013 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 MEDIA_GPU_IPC_CLIENT_GPU_VIDEO_ENCODE_ACCELERATOR_HOST_H_
 #define MEDIA_GPU_IPC_CLIENT_GPU_VIDEO_ENCODE_ACCELERATOR_HOST_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
 #include "base/threading/non_thread_safe.h"
 #include "gpu/config/gpu_info.h"
 #include "gpu/ipc/client/command_buffer_proxy_impl.h"
 #include "ipc/ipc_listener.h"
 #include "media/video/video_encode_accelerator.h"
 
 namespace gfx {
 class Size;
 }  // namespace gfx
 
@@ skipping 71 matching lines @@
   void OnNotifyError(Error error);
 
   scoped_refptr<gpu::GpuChannelHost> channel_;
 
   // Route ID for the associated encoder in the GPU process.
   int32_t encoder_route_id_;
 
   // The client that will receive callbacks from the encoder.
   Client* client_;
 
+  // Protect |impl_|. |impl_| is used on media thread, but it can be invalidated
+  // on main thread.
+  base::Lock impl_lock_;
+
   // Unowned reference to the gpu::CommandBufferProxyImpl that created us.
   // |this| registers as a DeletionObserver of |impl_|, so the reference is
   // always valid as long as it is not NULL.
   gpu::CommandBufferProxyImpl* impl_;
 
   // VideoFrames sent to the encoder.
   // base::IDMap not used here, since that takes pointers, not scoped_refptr.
   typedef base::hash_map<int32_t, scoped_refptr<VideoFrame>> FrameMap;
   FrameMap frame_map_;
 
   // ID serial number for the next frame to send to the GPU process.
   int32_t next_frame_id_;
 
+  // Task runner for tasks that should run on the thread this class is
+  // constructed.
+  scoped_refptr<base::SingleThreadTaskRunner> media_task_runner_;
+
   // WeakPtr factory for posting tasks back to itself.
   base::WeakPtrFactory<GpuVideoEncodeAcceleratorHost> weak_this_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuVideoEncodeAcceleratorHost);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_GPU_IPC_CLIENT_GPU_VIDEO_ENCODE_ACCELERATOR_HOST_H_