Add MediaGpuChannelManager::LookupChannel().

content/renderer/media/renderer_gpu_video_accelerator_factories.cc

Index: content/renderer/media/renderer_gpu_video_accelerator_factories.cc
diff --git a/content/renderer/media/renderer_gpu_video_accelerator_factories.cc b/content/renderer/media/renderer_gpu_video_accelerator_factories.cc
index 1fbdb829d93a9dbf2c364afb21ed0418bedf90fc..dff894ac58efdab4fd319e578aaeb671c15890df 100644
--- a/content/renderer/media/renderer_gpu_video_accelerator_factories.cc
+++ b/content/renderer/media/renderer_gpu_video_accelerator_factories.cc
@@ -127,6 +127,13 @@ base::UnguessableToken RendererGpuVideoAcceleratorFactories::GetChannelToken() {
   return channel_token_;
 }
 
+int32_t RendererGpuVideoAcceleratorFactories::GetCommandBufferRouteId() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (!context_provider_)

[dcheng, 2017/01/10 06:03:42]

How come most other things use CheckContextLost()?

[sandersd (OOO until July 31), 2017/01/10 23:54:14]

I don't care if the returned route_id is invalid, since it's also tied to a
channel which is separately queried. That said, it's probably better to be
consistent, so I've changed it.

+    return 0;
+  return context_provider_->GetCommandBufferProxy()->route_id();
+}
+
 std::unique_ptr<media::VideoDecodeAccelerator>
 RendererGpuVideoAcceleratorFactories::CreateVideoDecodeAccelerator() {
   DCHECK(video_accelerator_enabled_);