services/ui: Detect when a video is playing

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 7d683bd2c065be64c7ef417a403d8abb4a18e9d6..7c19d2a4a1769cd0bb2f63b7375e97d8dc43043e 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -95,6 +95,7 @@ Layer::Layer()
       force_render_surface_for_testing_(false),
       subtree_property_changed_(false),
       layer_property_changed_(false),
+      may_contain_video_(false),
       safe_opaque_background_color_(0),
       draw_blend_mode_(SkXfermode::kSrcOver_Mode),
       num_unclipped_descendants_(0) {}
@@ -1144,6 +1145,7 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   // property trees. So, it is enough to check it only for the current layer.
   if (subtree_property_changed_ || layer_property_changed_)
     layer->NoteLayerPropertyChanged();
+  layer->set_may_contain_video(may_contain_video_);
   layer->SetMasksToBounds(inputs_.masks_to_bounds);
   layer->set_main_thread_scrolling_reasons(
       inputs_.main_thread_scrolling_reasons);
@@ -1598,6 +1600,13 @@ void Layer::SetLayerPropertyChanged() {
   SetNeedsPushProperties();
 }
 
+void Layer::SetMayContainVideo(bool yes) {
+  if (may_contain_video_ == yes)
+    return;
+  may_contain_video_ = yes;
+  SetNeedsPushProperties();
+}
+
 bool Layer::FilterIsAnimating() const {
   return GetAnimationHost()->IsAnimatingFilterProperty(
       element_id(), GetElementTypeForAnimation());