mus-gpu: Talk to the GpuHost from the IO thread.

services/ui/gpu/gpu_service.cc

Index: services/ui/gpu/gpu_service.cc
diff --git a/services/ui/gpu/gpu_service.cc b/services/ui/gpu/gpu_service.cc
index 496de6b841a54d77a620665d22881efc0b79644f..2bdfe628b93a9c1bafb5d42d44786e2a83751465 100644
--- a/services/ui/gpu/gpu_service.cc
+++ b/services/ui/gpu/gpu_service.cc
@@ -75,8 +75,6 @@ void GpuService::InitializeWithHost(mojom::GpuHostPtr gpu_host,
                                     gpu::SyncPointManager* sync_point_manager,
                                     base::WaitableEvent* shutdown_event) {
   DCHECK(CalledOnValidThread());
-  DCHECK(!gpu_host_);
-  gpu_host_ = std::move(gpu_host);
   gpu_preferences_ = preferences;
   gpu_info_.video_decode_accelerator_capabilities =
       media::GpuVideoDecodeAccelerator::GetCapabilities(gpu_preferences_);
@@ -85,7 +83,12 @@ void GpuService::InitializeWithHost(mojom::GpuHostPtr gpu_host,
   gpu_info_.jpeg_decode_accelerator_supported =
       media::GpuJpegDecodeAcceleratorFactoryProvider::
           IsAcceleratedJpegDecodeSupported();
-  gpu_host_->DidInitialize(gpu_info_);
+  gpu_host->DidInitialize(gpu_info_);
+
+  task_tracker_.PostTask(
+      io_runner_.get(), FROM_HERE,
+      base::Bind(&GpuService::BindGpuHostOnIO, base::Unretained(this),
+                 base::Passed(gpu_host.PassInterface())));
 
   sync_point_manager_ = sync_point_manager;
   if (!sync_point_manager_) {
@@ -111,6 +114,13 @@ void GpuService::Bind(mojom::GpuServiceRequest request) {
   bindings_.AddBinding(this, std::move(request));
 }
 
+void GpuService::BindGpuHostOnIO(mojom::GpuHostPtrInfo ptr_info) {
+  DCHECK(io_runner_->RunsTasksOnCurrentThread());
+  mojom::GpuHostPtr gpu_host;
+  gpu_host.Bind(std::move(ptr_info));
+  gpu_host_ = mojom::ThreadSafeGpuHostPtr::Create(std::move(gpu_host));

[Ken Rockot(use gerrit already), 2017/03/21 22:40:35]

The ThreadSafeInterfacePtr itself is thread-safe, but |gpu_host_| storage is
not. This would need to be guarded by a lock now, wouldn't it?

You can avoid this by instead calling, in the constructor:

gpu_host_ = mojom::ThreadSafeGpuHostPtr::Create(gpu_host.PassInterface(),
io_runner_);

I don't think you'd need a CancelableTaskTracker then either?

[sadrul, 2017/03/21 22:43:10]

Ooh, so ThreadSafe* can be take a task-runner of a different thread? That's
awesome :) Yep, that simplifies this a lot. I will make that change. Thanks!

[sadrul, 2017/03/21 23:14:17]

Done.

+}
+
 void GpuService::CreateGpuMemoryBuffer(
     gfx::GpuMemoryBufferId id,
     const gfx::Size& size,
@@ -143,35 +153,35 @@ void GpuService::GetVideoMemoryUsageStats(
 }
 
 void GpuService::DidCreateOffscreenContext(const GURL& active_url) {
-  gpu_host_->DidCreateOffscreenContext(active_url);
+  (*gpu_host_)->DidCreateOffscreenContext(active_url);
 }
 
 void GpuService::DidDestroyChannel(int client_id) {
   media_gpu_channel_manager_->RemoveChannel(client_id);
-  gpu_host_->DidDestroyChannel(client_id);
+  (*gpu_host_)->DidDestroyChannel(client_id);
 }
 
 void GpuService::DidDestroyOffscreenContext(const GURL& active_url) {
-  gpu_host_->DidDestroyOffscreenContext(active_url);
+  (*gpu_host_)->DidDestroyOffscreenContext(active_url);
 }
 
 void GpuService::DidLoseContext(bool offscreen,
                                 gpu::error::ContextLostReason reason,
                                 const GURL& active_url) {
-  gpu_host_->DidLoseContext(offscreen, reason, active_url);
+  (*gpu_host_)->DidLoseContext(offscreen, reason, active_url);
 }
 
 void GpuService::StoreShaderToDisk(int client_id,
                                    const std::string& key,
                                    const std::string& shader) {
-  gpu_host_->StoreShaderToDisk(client_id, key, shader);
+  (*gpu_host_)->StoreShaderToDisk(client_id, key, shader);
 }
 
 #if defined(OS_WIN)
 void GpuService::SendAcceleratedSurfaceCreatedChildWindow(
     gpu::SurfaceHandle parent_window,
     gpu::SurfaceHandle child_window) {
-  gpu_host_->SetChildSurface(parent_window, child_window);
+  (*gpu_host_)->SetChildSurface(parent_window, child_window);
 }
 #endif