Add MediaGpuChannelManager::LookupChannel().

media/mojo/services/mojo_video_decoder_service.cc

Index: media/mojo/services/mojo_video_decoder_service.cc
diff --git a/media/mojo/services/mojo_video_decoder_service.cc b/media/mojo/services/mojo_video_decoder_service.cc
index 7a94c575413c67f3552f8bf84f0800d20123844c..84b0308804deae8fd28ed50b4eaaf8a4772c2efb 100644
--- a/media/mojo/services/mojo_video_decoder_service.cc
+++ b/media/mojo/services/mojo_video_decoder_service.cc
@@ -31,15 +31,17 @@ MojoVideoDecoderService::~MojoVideoDecoderService() {}
 
 void MojoVideoDecoderService::Construct(
     mojom::VideoDecoderClientAssociatedPtrInfo client,
-    mojo::ScopedDataPipeConsumerHandle decoder_buffer_pipe) {
+    mojo::ScopedDataPipeConsumerHandle decoder_buffer_pipe,
+    mojom::CommandBufferIdPtr command_buffer_id) {
   DVLOG(1) << __func__;
 
+  // TODO(sandersd): Enter an error state.

[dcheng, 2017/01/11 09:14:18]

What does this mean?

[sandersd (OOO until July 31), 2017/01/11 21:33:09]

The client should not have called this method at this time; we should probably
be disconnecting them. At the time this was written we didn't have a complete
story for how such errors should be handled. (We have most of a plan now, but it
wasn't critical to include in this CL.)

[dcheng, 2017/01/11 22:01:59]

Out of curiosity, how will they be handled? =)

[sandersd (OOO until July 31), 2017/01/11 22:21:31]

The plan is to pass a callback into the constructor that will close the string
binding (which for media services is owned by a StrongBindingSet); we will just
call that for incorrect API usage. In any egregious cases (I don't think
MojoVideoDecoder has any), the plan is to also call ReportBadMessage().

   if (decoder_)
     return;
 
   // TODO(sandersd): Provide callback for requesting a GpuCommandBufferStub.
   decoder_ = mojo_media_client_->CreateVideoDecoder(
-      base::ThreadTaskRunnerHandle::Get());
+      base::ThreadTaskRunnerHandle::Get(), std::move(command_buffer_id));
 
   client_.Bind(std::move(client));