Implemented new fence syncs which replaces the old sync points.

gpu/command_buffer/client/gpu_control.h

Index: gpu/command_buffer/client/gpu_control.h
diff --git a/gpu/command_buffer/client/gpu_control.h b/gpu/command_buffer/client/gpu_control.h
index 7065d1edb44c27e6904166091e2a4ab299d01819..700015216039c1659fe6511c052f088512752d23 100644
--- a/gpu/command_buffer/client/gpu_control.h
+++ b/gpu/command_buffer/client/gpu_control.h
@@ -96,6 +96,14 @@ class GPU_EXPORT GpuControl {
   virtual CommandBufferNamespace GetNamespaceID() const = 0;
   virtual uint64_t GetCommandBufferID() const = 0;
 
+  // Fence Syncs use release counters at a context level, these fence syncs
+  // need to be flushed before they can be shared with other contexts across
+  // channels. Subclasses should implement these functions and take care of
+  // figuring out when a fence sync has been flushed.
+  virtual uint64_t GenerateFenceSyncRelease() = 0;
+  virtual bool IsFenceSyncRelease(uint64_t release) = 0;
+  virtual bool IsFenceSyncFlushed(uint64_t release) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(GpuControl);
 };