GPU: Adding sync points for cross-channel synchronization

content/common/gpu/gpu_command_buffer_stub.h

Index: content/common/gpu/gpu_command_buffer_stub.h
diff --git a/content/common/gpu/gpu_command_buffer_stub.h b/content/common/gpu/gpu_command_buffer_stub.h
index 2c81c98ac6abed12d3ee487a700a633f719a07b5..09c88bda53c15469a33b761c84fe0af13477c62a 100644
--- a/content/common/gpu/gpu_command_buffer_stub.h
+++ b/content/common/gpu/gpu_command_buffer_stub.h
@@ -167,6 +167,10 @@ class GpuCommandBufferStub
   void AddDestructionObserver(DestructionObserver* observer);
   void RemoveDestructionObserver(DestructionObserver* observer);
 
+  // Associates a sync point to this stub. When the stub is destroyed, it will
+  // retire all sync points that haven't been previously retired.
+  void AddSyncPoint(uint32 sync_point);
+
  private:
   void Destroy();
 
@@ -205,6 +209,10 @@ class GpuCommandBufferStub
   void OnDiscardBackbuffer();
   void OnEnsureBackbuffer();
 
+  void OnRetireSyncPoint(uint32 sync_point);
+  void OnWaitSyncPoint(uint32 sync_point);
+  void OnSyncPointRetired();
+
   void OnSetClientHasMemoryAllocationChangedCallback(bool);
 
   void OnReschedule();
@@ -255,6 +263,9 @@ class GpuCommandBufferStub
 
   ObserverList<DestructionObserver> destruction_observers_;
 
+  // A queue of sync points associated with this stub.
+  std::deque<uint32> sync_points_;
+
   DISALLOW_COPY_AND_ASSIGN(GpuCommandBufferStub);
 };