Mac ÜC: Enable back-pressure for the browser compositor

content/browser/compositor/browser_compositor_output_surface.cc

Index: content/browser/compositor/browser_compositor_output_surface.cc
diff --git a/content/browser/compositor/browser_compositor_output_surface.cc b/content/browser/compositor/browser_compositor_output_surface.cc
index b1cdd90e54e068b94c6e7ffe509192199beb3863..40576b2aeaf2e6e979db93c96ea0ca57380433f8 100644
--- a/content/browser/compositor/browser_compositor_output_surface.cc
+++ b/content/browser/compositor/browser_compositor_output_surface.cc
@@ -70,6 +70,14 @@ bool BrowserCompositorOutputSurface::BindToClient(
   return true;
 }
 
+void BrowserCompositorOutputSurface::OnSwapBuffersComplete() {
+  // On Mac, delay acknowledging the swap to the output surface client until
+  // it has been drawn.
+#if !defined(OS_MACOSX)
+  cc::OutputSurface::OnSwapBuffersComplete();
+#endif
+}
+
 void BrowserCompositorOutputSurface::OnUpdateVSyncParameters(
     base::TimeTicks timebase,
     base::TimeDelta interval) {
@@ -90,4 +98,10 @@ void BrowserCompositorOutputSurface::SetReflector(ReflectorImpl* reflector) {
   reflector_ = reflector;
 }
 
+#if defined(OS_MACOSX)
+void BrowserCompositorOutputSurface::OnSurfaceDisplayed() {
+  cc::OutputSurface::OnSwapBuffersComplete();
+}
+#endif
+
 }  // namespace content