Added method to synchronize command buffers within GpuControl.

gpu/command_buffer/tests/gl_manager.h

Index: gpu/command_buffer/tests/gl_manager.h
diff --git a/gpu/command_buffer/tests/gl_manager.h b/gpu/command_buffer/tests/gl_manager.h
index 10a067460e283155d9d07aebbf37610aaf92802e..134550148890f83857959b8f42df5beff234a3d0 100644
--- a/gpu/command_buffer/tests/gl_manager.h
+++ b/gpu/command_buffer/tests/gl_manager.h
@@ -133,6 +133,7 @@ class GLManager : private 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;