services/ui: Detect when a video is playing

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 6821f12d8bd5deac88f0e7902058ee7c471b475d..2fa1e9e261e6d5742b2a10ed9d684342155d91e7 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -471,6 +471,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void SetLayerPropertyChanged();
   bool layer_property_changed() const { return layer_property_changed_; }
 
+  void SetMayContainVideo(bool yes);
+
   void DidBeginTracing();
 
   int num_copy_requests_in_target_subtree();
@@ -708,6 +710,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   bool force_render_surface_for_testing_ : 1;
   bool subtree_property_changed_ : 1;
   bool layer_property_changed_ : 1;
+  bool may_contain_video_ : 1;
   SkColor safe_opaque_background_color_;
   // draw_blend_mode may be different than blend_mode_,
   // when a RenderSurface re-parents the layer's blend_mode.