Clean up Mac swap acknowledgement code

content/browser/compositor/gpu_browser_compositor_output_surface.h

Index: content/browser/compositor/gpu_browser_compositor_output_surface.h
diff --git a/content/browser/compositor/gpu_browser_compositor_output_surface.h b/content/browser/compositor/gpu_browser_compositor_output_surface.h
index 7b4f242812244401c5c1c50aca056b80d691b048..dd6f5ff44e14af0ea4527eea4fbe4f04d511798a 100644
--- a/content/browser/compositor/gpu_browser_compositor_output_surface.h
+++ b/content/browser/compositor/gpu_browser_compositor_output_surface.h
@@ -36,6 +36,9 @@ class GpuBrowserCompositorOutputSurface
  protected:
   // BrowserCompositorOutputSurface:
   void OnReflectorChanged() override;
+  void OnGpuSwapBuffersCompleted(
+      const std::vector<ui::LatencyInfo>& latency_info,
+      gfx::SwapResult result) override;
 
   // cc::OutputSurface implementation.
   void SwapBuffers(cc::CompositorFrame* frame) override;
@@ -43,7 +46,6 @@ class GpuBrowserCompositorOutputSurface
   bool SurfaceIsSuspendForRecycle() const override;
 
 #if defined(OS_MACOSX)
-  void OnSurfaceDisplayed() override;
   void SetSurfaceSuspendedForRecycle(bool suspended) override;
   bool SurfaceShouldNotShowFramesAfterSuspendForRecycle() const override;
   enum ShouldShowFramesState {
@@ -61,9 +63,6 @@ class GpuBrowserCompositorOutputSurface
 #endif
 
   CommandBufferProxyImpl* GetCommandBufferProxy();
-  virtual void OnSwapBuffersCompleted(
-      const std::vector<ui::LatencyInfo>& latency_info,
-      gfx::SwapResult result);
 
   base::CancelableCallback<void(const std::vector<ui::LatencyInfo>&,
                                 gfx::SwapResult)>