Add embedder api for participating in gpu logic

content/public/gpu/gpu_service_registry.h

+// 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.
+
+#ifndef CONTENT_PUBLIC_GPU_GPU_SERVICE_REGISTRY_H_
+#define CONTENT_PUBLIC_GPU_GPU_SERVICE_REGISTRY_H_
+
+#include "content/common/content_export.h"
+
+namespace content {
+class ServiceRegistry;
+
+// Get ServiceRegistry registered via ContentGpuClient::RegisterMojoServices().
+// This must be called on IO thread.
+CONTENT_EXPORT ServiceRegistry* GetGpuServiceRegistry();

[jam, 2016/01/28 16:47:36]

why is this needed? i.e. why isn't the ContentGpuClient method enough?

it's hard to see how this will be used since the change is just a skeleton. can
you add the arc++ code that will use this?

[kcwu, 2016/01/28 17:55:30]

Since there is already a mojo ipc channel with ServiceRegistry established
between GpuProcessHost on browser process and GpuChildThread on GPU process. I
want to register a mojo service in the GPU process (via
ServiceRegistry::AddService in GpuChildThread) and then use the registered
service in the browser process (get the service via
ServiceRegistry::ConnectToRemoteService). So this function is needed and is
called in browser process.

The code to utilize them is not ready yet.

[jam, 2016/01/28 21:13:39]

If it's called in the browser process, then it should be in
content/public/browser.
Please upload one version that works. At that point, we can split it out into
smaller patches. But right now, preliminary patches that don't have a working
system aren't ready for review because code is in the wrong processes.

[kcwu, 2016/01/29 17:22:44]

The CL of embedder call is http://crrev.com/1641353003. I'm still revising that
CL, but it already can work what I described (register service in the GPU
process and query service in the browser process).

+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_GPU_GPU_SERVICE_REGISTRY_H_