Add interfaces to send ReturnData from decoder to client

This adds HandleReturnData to DecoderClient to allow the
WebGPUDecoder to send binary blobs of return commands back
to the WebGPUImplementation. Its implementation in the
InProcessCommandBuffer and the ProxyCommandBufferImpl
forward the data to the GpuControlClient interface. The
WebGPUImplementation will receive the return command stream
via GpuControlClient::GpuControlOnReturnData.

Bug: 877147
Change-Id: Ic7983b9d7b6dd15680427162762bc3bc39bd52fd
Reviewed-on: https://chromium-review.googlesource.com/c/1481615
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636500}
27 files changed