Mac ÜC: Enable back-pressure for the browser compositor

content/browser/compositor/browser_compositor_output_surface.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/compositor/browser_compositor_output_surface.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 52 matching lines @@
   if (!OutputSurface::BindToClient(client))
     return false;
 
   output_surface_map_->AddWithID(this, surface_id_);
   if (reflector_)
     reflector_->OnSourceSurfaceReady(this);
   vsync_manager_->AddObserver(this);
   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) {
   DCHECK(CalledOnValidThread());
   DCHECK(HasClient());
   CommitVSyncParameters(timebase, interval);
 }
 
 void BrowserCompositorOutputSurface::OnUpdateVSyncParametersFromGpu(
     base::TimeTicks timebase,
     base::TimeDelta interval) {
   DCHECK(CalledOnValidThread());
   DCHECK(HasClient());
   vsync_manager_->UpdateVSyncParameters(timebase, interval);
 }
 
 void BrowserCompositorOutputSurface::SetReflector(ReflectorImpl* reflector) {
   reflector_ = reflector;
 }
 
+#if defined(OS_MACOSX)
+void BrowserCompositorOutputSurface::OnSurfaceDisplayed() {
+  cc::OutputSurface::OnSwapBuffersComplete();
+}
+#endif
+
 }  // namespace content