Added method to synchronize command buffers within GpuControl.

gpu/gles2_conform_support/egl/display.h

Index: gpu/gles2_conform_support/egl/display.h
diff --git a/gpu/gles2_conform_support/egl/display.h b/gpu/gles2_conform_support/egl/display.h
index 66d0d5b5d5f037712bbfff18e9b78e4c62aae9be..4196df307caae691015d7a0d5d81569023ad93ef 100644
--- a/gpu/gles2_conform_support/egl/display.h
+++ b/gpu/gles2_conform_support/egl/display.h
@@ -99,6 +99,7 @@ class Display : private gpu::GpuControl {
   void SignalQuery(uint32_t query, const base::Closure& callback) override;
   void SetLock(base::Lock*) override;
   bool IsGpuChannelLost() override;
+  void SynchronizeCommandBuffer() override;
   gpu::CommandBufferNamespace GetNamespaceID() const override;
   uint64_t GetCommandBufferID() const override;
   int32_t GetExtraCommandBufferData() const override;