Reland of gpu: GPU service scheduler.

services/ui/gpu/gpu_service.h

Index: services/ui/gpu/gpu_service.h
diff --git a/services/ui/gpu/gpu_service.h b/services/ui/gpu/gpu_service.h
index d6e2d3f583a1e7e3bb4990f9f2f6837c99b5beff..bb42a84b901506951b2ca3b1a7aff69ae25e2dce 100644
--- a/services/ui/gpu/gpu_service.h
+++ b/services/ui/gpu/gpu_service.h
@@ -29,6 +29,7 @@
 namespace gpu {
 class GpuMemoryBufferFactory;
 class GpuWatchdogThread;
+class Scheduler;
 class SyncPointManager;
 }
 
@@ -183,6 +184,8 @@ class GpuService : public gpu::GpuChannelManagerDelegate,
   std::unique_ptr<gpu::SyncPointManager> owned_sync_point_manager_;
   gpu::SyncPointManager* sync_point_manager_ = nullptr;
 
+  std::unique_ptr<gpu::Scheduler> scheduler_;
+
   // An event that will be signalled when we shutdown. On some platforms it
   // comes from external sources.
   std::unique_ptr<base::WaitableEvent> owned_shutdown_event_;