Disable Vsync when Aero Glass is enabled.

content/common/gpu/image_transport_surface.cc

Index: content/common/gpu/image_transport_surface.cc
diff --git a/content/common/gpu/image_transport_surface.cc b/content/common/gpu/image_transport_surface.cc
index 4ce6f4020317ce81490964173d0b2e0fc8f348c2..7a2932385debd1d9a6a873355900a38db9b40122 100644
--- a/content/common/gpu/image_transport_surface.cc
+++ b/content/common/gpu/image_transport_surface.cc
@@ -19,6 +19,10 @@
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_switches.h"
 
+#if defined(OS_WIN)
+#include "ui/base/win/shell.h"
+#endif
+
 namespace content {
 
 ImageTransportSurface::ImageTransportSurface() {}
@@ -164,6 +168,14 @@ bool ImageTransportHelper::MakeCurrent() {
 }
 
 void ImageTransportHelper::SetSwapInterval(gfx::GLContext* context) {
+#if defined(OS_WIN)
+  // If Aero Glass is enabled, then the renderer will handle ratelimiting and
+  // there's no tearing, so waiting for vsync is unnecessary.
+  if (ui::win::IsAeroGlassEnabled()) {
+    context->SetSwapInterval(0);
+    return;
+  }
+#endif
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kDisableGpuVsync))
     context->SetSwapInterval(0);
   else