Add MediaGpuChannelManager::LookupChannel().

media/gpu/ipc/service/media_gpu_channel_manager.h

 // Copyright 2016 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_SERVICE_MEDIA_GPU_CHANNEL_MANAGER_H_
 #define MEDIA_GPU_IPC_SERVICE_MEDIA_GPU_CHANNEL_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <unordered_map>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/unguessable_token.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_sender.h"
 #include "media/video/video_decode_accelerator.h"
 
 namespace gpu {
+class GpuChannel;
 class GpuChannelManager;
 }
 
 namespace media {
 
 class MediaGpuChannel;
 
 class MediaGpuChannelManager
     : public base::SupportsWeakPtr<MediaGpuChannelManager> {
  public:
   explicit MediaGpuChannelManager(gpu::GpuChannelManager* channel_manager);
   ~MediaGpuChannelManager();
 
   void AddChannel(int32_t client_id);
   void RemoveChannel(int32_t client_id);
   void DestroyAllChannels();
 
+  // TODO(sandersd): Should we expose the MediaGpuChannel instead?
+  gpu::GpuChannel* LookupChannel(const base::UnguessableToken& channel_token);
+
  private:
   gpu::GpuChannelManager* const channel_manager_;
   std::unordered_map<int32_t, std::unique_ptr<MediaGpuChannel>>
       media_gpu_channels_;
+  std::map<base::UnguessableToken, int32_t> token_to_channel_;
+  std::map<int32_t, base::UnguessableToken> channel_to_token_;
   DISALLOW_COPY_AND_ASSIGN(MediaGpuChannelManager);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_GPU_IPC_SERVICE_MEDIA_GPU_CHANNEL_MANAGER_H_