Add MediaGpuChannelManager::LookupChannel().

media/gpu/ipc/service/media_gpu_channel_manager.cc

 // 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.
 
 #include "media/gpu/ipc/service/media_gpu_channel_manager.h"
 
 #include <memory>
 #include <utility>
 
 #include "gpu/ipc/service/gpu_channel.h"
 #include "gpu/ipc/service/gpu_channel_manager.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/param_traits_macros.h"
 #include "media/gpu/ipc/service/gpu_video_decode_accelerator.h"
 #include "media/gpu/ipc/service/gpu_video_encode_accelerator.h"
 #include "media/gpu/ipc/service/media_gpu_channel.h"
 
 namespace media {
 
 MediaGpuChannelManager::MediaGpuChannelManager(
     gpu::GpuChannelManager* channel_manager)
     : channel_manager_(channel_manager) {}
 
 MediaGpuChannelManager::~MediaGpuChannelManager() {}
 
 void MediaGpuChannelManager::AddChannel(int32_t client_id) {
   gpu::GpuChannel* gpu_channel = channel_manager_->LookupChannel(client_id);
   DCHECK(gpu_channel);
+  base::UnguessableToken channel_token = base::UnguessableToken::Create();
   std::unique_ptr<MediaGpuChannel> media_gpu_channel(
-      new MediaGpuChannel(gpu_channel));
+      new MediaGpuChannel(gpu_channel, channel_token));
   gpu_channel->SetUnhandledMessageListener(media_gpu_channel.get());
   media_gpu_channels_[client_id] = std::move(media_gpu_channel);
+  channel_to_token_[client_id] = channel_token;
+  token_to_channel_[channel_token] = client_id;
 }
 
 void MediaGpuChannelManager::RemoveChannel(int32_t client_id) {
   media_gpu_channels_.erase(client_id);
+  const auto it = channel_to_token_.find(client_id);
+  if (it != channel_to_token_.end()) {
+    token_to_channel_.erase(it->second);
+    channel_to_token_.erase(it);
+  }
 }
 
 void MediaGpuChannelManager::DestroyAllChannels() {
   media_gpu_channels_.clear();
+  token_to_channel_.clear();
+  channel_to_token_.clear();
+}
+
+gpu::GpuChannel* MediaGpuChannelManager::LookupChannel(
+    const base::UnguessableToken& channel_token) {
+  const auto it = token_to_channel_.find(channel_token);
+  if (it == token_to_channel_.end())
+    return nullptr;
+  return channel_manager_->LookupChannel(it->second);
 }
 
 }  // namespace media