content/gpu: Set up a mojom connection between browser and gpu.

content/gpu/gpu_child_thread.cc

 // Copyright (c) 2012 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.
 
 #include "content/gpu/gpu_child_thread.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 185 matching lines @@
 
 void GpuChildThread::Init(const base::Time& process_start_time) {
   process_start_time_ = process_start_time;
 
 #if defined(OS_ANDROID)
   // When running in in-process mode, this has been set in the browser at
   // ChromeBrowserMainPartsAndroid::PreMainMessageLoopRun().
   if (!in_browser_process_)
     media::SetMediaClientAndroid(GetContentClient()->GetMediaClientAndroid());
 #endif
-  // We don't want to process any incoming interface requests until
-  // OnInitialize() is invoked.

[jbauman, 2017/01/11 01:49:22]

Just checking, but is the reason we can remove this that mojo messages are now
processed in order with the GpuMsg_Initialize IPC message?

[sadrul, 2017/01/11 01:55:46]

The Pause/Resume was added in https://crrev.com/402996, to make sure
OnInitialize() is called before any of the mojo requests are processed.
https://crrev.com/406761 then moved the mojo registrations in OnInitialize(),
which means the mojo requests could not be processed before OnInitialize() is
called anyway. So I think that makes it safe to remove Pause/Remove now.

This is also necessary because OnInitialize() itself will be replaced by a mojom
call (see more details in https://codereview.chromium.org/2612623002/), which
means this needs to allow processing mojo requests from the start.

I have added rockot@ to the reviewer list to make sure this reasoning is OK, and
there isn't a better way for doing this.

[Ken Rockot(use gerrit already), 2017/01/11 18:17:00]

This rationale seems kind of circular to me. I don't think it's safe to remove
this behavior. r406761 was able to move interface registration to OnInitialize
precisely *because* we pause the registry binding here. If we don't pause it,
interface requests can be dispatched (and thus those interfaces can be bound and
receive messages) before OnInitialize() runs.

-  GetInterfaceRegistry()->PauseBinding();
 
   if (GetContentClient()->gpu())  // NULL in tests.
     GetContentClient()->gpu()->Initialize(this);
+  channel()->AddAssociatedInterface(base::Bind(
+      &GpuChildThread::CreateGpuMainService, base::Unretained(this)));
 }
 
 void GpuChildThread::OnFieldTrialGroupFinalized(const std::string& trial_name,
                                                 const std::string& group_name) {
   Send(new GpuHostMsg_FieldTrialActivated(trial_name));
 }
 
+void GpuChildThread::CreateGpuMainService(
+    ui::mojom::GpuMainAssociatedRequest request) {
+  // TODO(sad): Implement.
+}
+
 bool GpuChildThread::Send(IPC::Message* msg) {
   // The GPU process must never send a synchronous IPC message to the browser
   // process. This could result in deadlock.
   DCHECK(!msg->is_sync());
 
   return ChildThreadImpl::Send(msg);
 }
 
 bool GpuChildThread::OnControlMessageReceived(const IPC::Message& msg) {
   bool handled = true;
@@ skipping 133 matching lines @@
 
   GetInterfaceRegistry()->AddInterface(base::Bind(
       &GpuChildThread::BindServiceFactoryRequest, base::Unretained(this)));
 
   if (GetContentClient()->gpu()) {  // NULL in tests.
     GetContentClient()->gpu()->ExposeInterfacesToBrowser(GetInterfaceRegistry(),
                                                          gpu_preferences);
     GetContentClient()->gpu()->ConsumeInterfacesFromBrowser(
         GetRemoteInterfaces());
   }
-
-  GetInterfaceRegistry()->ResumeBinding();
 }
 
 void GpuChildThread::OnFinalize() {
   // Quit the GPU process
   base::MessageLoop::current()->QuitWhenIdle();
 }
 
 void GpuChildThread::OnCollectGraphicsInfo() {
   if (dead_on_arrival_)
     return;
@@ skipping 138 matching lines @@
 
 void GpuChildThread::BindServiceFactoryRequest(
     service_manager::mojom::ServiceFactoryRequest request) {
   DVLOG(1) << "GPU: Binding service_manager::mojom::ServiceFactoryRequest";
   DCHECK(service_factory_);
   service_factory_bindings_.AddBinding(service_factory_.get(),
                                        std::move(request));
 }
 
 }  // namespace content