[Do not submit] D3DKMTWaitForVerticalBlankEvent VSync prototype

gpu/ipc/service/gpu_command_buffer_stub.h

Index: gpu/ipc/service/gpu_command_buffer_stub.h
diff --git a/gpu/ipc/service/gpu_command_buffer_stub.h b/gpu/ipc/service/gpu_command_buffer_stub.h
index 91b8dfe1c36ff3978808b7af5933d2ee276e8c31..08357e2f6806a515c33bb6fb70893652b77f0537 100644
--- a/gpu/ipc/service/gpu_command_buffer_stub.h
+++ b/gpu/ipc/service/gpu_command_buffer_stub.h
@@ -16,6 +16,7 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "gpu/command_buffer/common/command_buffer_id.h"
 #include "gpu/command_buffer/common/constants.h"
@@ -50,6 +51,7 @@ namespace gpu {
 
 class GpuChannel;
 struct WaitForCommandState;
+class GpuVSyncProvider;
 
 class GPU_EXPORT GpuCommandBufferStub
     : public IPC::Listener,
@@ -93,9 +95,18 @@ class GPU_EXPORT GpuCommandBufferStub
   void DidSwapBuffersComplete(SwapBuffersCompleteParams params) override;
   const gles2::FeatureInfo* GetFeatureInfo() const override;
   void SetLatencyInfoCallback(const LatencyInfoCallback& callback) override;
+  // This is called from VSyncProvider to update parameters for generating
+  // timer-based VSync signals on the browser side.
   void UpdateVSyncParameters(base::TimeTicks timebase,
                              base::TimeDelta interval) override;
 
+  // This is called from GpuVSyncProvider with actual GPU VSync signals.
+  void UpdateGpuVSync(base::TimeTicks timestamp);
+
+  // Send VSync signals or VSync parameters over IPC.
+  void SendUpdatedVSyncParameters(base::TimeTicks timebase,
+                                  base::TimeDelta interval);
+
   gles2::MemoryTracker* GetMemoryTracker() const;
 
   // Whether this command buffer can currently handle IPC messages.
@@ -188,6 +199,7 @@ class GPU_EXPORT GpuCommandBufferStub
   void OnCreateStreamTexture(uint32_t texture_id,
                              int32_t stream_id,
                              bool* succeeded);
+  void OnEnableVSync(bool enabled);
   void OnCommandProcessed();
   void OnParseError();
 
@@ -250,6 +262,21 @@ class GPU_EXPORT GpuCommandBufferStub
   std::unique_ptr<WaitForCommandState> wait_for_token_;
   std::unique_ptr<WaitForCommandState> wait_for_get_offset_;
 
+  bool gpu_vsync_signal_supported_;
+  std::unique_ptr<GpuVSyncProvider> vsync_provider_;
+
+#if defined(OS_WIN)
+  // TODO: This isn't ideal, but for now VSync interval is still
+  // provided via UpdateVSyncParameters on the main thread, but
+  // it needs to be passed along with VSync signal when VSync becomes
+  // available on background thread.
+  // The current solution is to temporarily store vsync_interval_.
+  // Perhaps this could be avoided by calculating the interval from
+  // consecutive VSync signals.
+  base::TimeDelta vsync_interval_;
+  base::Lock vsync_lock_;
+#endif  // defined(OS_WIN)
+
   DISALLOW_COPY_AND_ASSIGN(GpuCommandBufferStub);
 };