Compute damage rect for Cast video compositing

content/browser/compositor/gpu_process_transport_factory.cc

Index: content/browser/compositor/gpu_process_transport_factory.cc
diff --git a/content/browser/compositor/gpu_process_transport_factory.cc b/content/browser/compositor/gpu_process_transport_factory.cc
index 23c4cbd818916f0f8586f6be37f7d3157ba92522..c4121a1fcc82f65a159c143b2fa66a48f1ed79e7 100644
--- a/content/browser/compositor/gpu_process_transport_factory.cc
+++ b/content/browser/compositor/gpu_process_transport_factory.cc
@@ -236,7 +236,8 @@ CreateOverlayCandidateValidator(gfx::AcceleratedWidget widget) {
     validator.reset(
         new display_compositor::CompositorOverlayCandidateValidatorOzone(
             std::move(overlay_candidates),
-            enable_overlay_flag == "single-fullscreen"));
+            enable_overlay_flag == "single-fullscreen",
+            enable_overlay_flag == "cast-underlay"));
   }
 #elif defined(OS_MACOSX)
   // Overlays are only supported through the remote layer API.