cc : Track ids for which active opacity always wins on property trees

cc/layers/solid_color_scrollbar_layer.cc

Index: cc/layers/solid_color_scrollbar_layer.cc
diff --git a/cc/layers/solid_color_scrollbar_layer.cc b/cc/layers/solid_color_scrollbar_layer.cc
index 3248cecbc353168d7de1a19823042231204b66bb..131e7735cb194a310363397636227267125f9cb7 100644
--- a/cc/layers/solid_color_scrollbar_layer.cc
+++ b/cc/layers/solid_color_scrollbar_layer.cc
@@ -70,6 +70,10 @@ bool SolidColorScrollbarLayer::OpacityCanAnimateOnImplThread() const {
   return true;
 }
 
+bool SolidColorScrollbarLayer::AlwaysUseActiveTreeOpacity() const {
+  return true;
+}
+
 int SolidColorScrollbarLayer::ScrollLayerId() const {
   return scroll_layer_id_;
 }