mac content shell drt: Hook up a dummy image transport

content/test/layouttest_support.cc

Index: content/test/layouttest_support.cc
diff --git a/content/test/layouttest_support.cc b/content/test/layouttest_support.cc
index a0d77b6ecbd0443d02b995e263b07aeb92ec65d2..3b573343a035252fe29f27bebcdd4043cad662f2 100644
--- a/content/test/layouttest_support.cc
+++ b/content/test/layouttest_support.cc
@@ -6,6 +6,7 @@
 
 #include "base/callback.h"
 #include "base/lazy_instance.h"
+#include "content/common/gpu/image_transport_surface.h"
 #include "content/renderer/devtools/devtools_client.h"
 #include "content/renderer/render_view_impl.h"
 #include "content/renderer/renderer_webapplicationcachehost_impl.h"
@@ -61,4 +62,10 @@ int GetLocalSessionHistoryLength(RenderView* render_view) {
       ->GetLocalSessionHistoryLengthForTesting();
 }
 
+void SetAllowOSMesaImageTransportForTesting() {
+#if defined(OS_MACOSX)
+  ImageTransportSurface::SetAllowOSMesaForTesting(true);
+#endif
+}
+
 }  // namespace content