GitLab

On ToT, RenderThreadImpl creates one "remote" mojom::VideoEncodeAcceleratorPtr
on main render thread and gives it to GpuVideoAcceleratorFactoriesImpl [1];
this factory gives it to the first constructed MojoVideoEncodeAccelerator;
this is good for the first time, but after that it'd be gone, the construction
of subsequent MojoVideoEncodeAccelerators will fail and we'll be falling back 
to software and/or the old IPC mechanism.

This CL changes that by adding a mojom VideoEncodeAcceleratorProvider interface,
which is bound along the chain:

 RenderThreadImpl --> gpu.mojom --> GpuClient --> gpu_service.mojom --> GpuService

GpuService finally bind the request to a new MojoVideoEncodeAcceleratorProvider 
(added in this CL as well).

GpuVideoAcceleratorFactoriesImpl uses this bound Provider to create 
MojoVideoEncodeAccelerators every time.

[1] https://cs.chromium.org/chromium/src/content/renderer/render_thread_impl.cc?dr=CSs&sq=package:chromium&l=1463

Bug: 736517
Change-Id: I3c753f951f120e1d2ffefb50a526fac15de6e881
Reviewed-on: https://chromium-review.googlesource.com/590513
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490658}