Make GPU back-pressure work with remote CALayers

content/common/gpu/image_transport_surface_mac.mm

Index: content/common/gpu/image_transport_surface_mac.mm
diff --git a/content/common/gpu/image_transport_surface_mac.mm b/content/common/gpu/image_transport_surface_mac.mm
index 3cfda14b93ed13e4045289cd1084064d9cdbdb72..c193f6f70d90739c232a638822fd7c97279cdad5 100644
--- a/content/common/gpu/image_transport_surface_mac.mm
+++ b/content/common/gpu/image_transport_surface_mac.mm
@@ -5,8 +5,6 @@
 #include "content/common/gpu/image_transport_surface_fbo_mac.h"
 
 #include "content/common/gpu/gpu_messages.h"
-#include "content/common/gpu/image_transport_surface_iosurface_mac.h"
-#include "content/common/gpu/image_transport_surface_calayer_mac.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_implementation.h"
@@ -49,10 +47,8 @@ scoped_refptr<gfx::GLSurface> ImageTransportSurface::CreateNativeSurface(
   switch (gfx::GetGLImplementation()) {
     case gfx::kGLImplementationDesktopGL:
     case gfx::kGLImplementationAppleGL:
-      // TODO(ccameron): If the remote layer API is supported on this system,
-      // use a CALayerStorageProvider instead of an IOSurfaceStorageProvider.
       return scoped_refptr<gfx::GLSurface>(new ImageTransportSurfaceFBO(
-          new IOSurfaceStorageProvider, manager, stub, surface_handle.handle));
+          manager, stub, surface_handle.handle));
     default:
       // Content shell in DRT mode spins up a gpu process which needs an
       // image transport surface, but that surface isn't used to read pixel