Clean up Mac swap acknowledgement code

content/browser/compositor/browser_compositor_output_surface.h

Index: content/browser/compositor/browser_compositor_output_surface.h
diff --git a/content/browser/compositor/browser_compositor_output_surface.h b/content/browser/compositor/browser_compositor_output_surface.h
index f5da02d56959802b86fd2d33076a505bec7c77f4..db815efdd313802c4c7d81cce3ccdb1448479207 100644
--- a/content/browser/compositor/browser_compositor_output_surface.h
+++ b/content/browser/compositor/browser_compositor_output_surface.h
@@ -14,6 +14,10 @@ namespace cc {
 class SoftwareOutputDevice;
 }
 
+namespace gfx {
+enum class SwapResult;
+}
+
 namespace content {
 class BrowserCompositorOverlayCandidateValidator;
 class ContextProviderCommandBuffer;
@@ -46,8 +50,12 @@ class CONTENT_EXPORT BrowserCompositorOutputSurface
   // compositors have started composition.
   virtual base::Closure CreateCompositionStartedCallback();
 
+  // Called when a swap completion is sent from the GPU process.
+  virtual void OnGpuSwapBuffersCompleted(
+      const std::vector<ui::LatencyInfo>& latency_info,
+      gfx::SwapResult result) = 0;
+
 #if defined(OS_MACOSX)
-  virtual void OnSurfaceDisplayed() = 0;
   virtual void SetSurfaceSuspendedForRecycle(bool suspended) = 0;
   virtual bool SurfaceShouldNotShowFramesAfterSuspendForRecycle() const = 0;
 #endif