Surface Synchronization: Distinguish between dependencies and references

cc/surfaces/surface.cc

Index: cc/surfaces/surface.cc
diff --git a/cc/surfaces/surface.cc b/cc/surfaces/surface.cc
index 3290f84bc1c1fd960e3e567394625f2e9bd74d81..a161eee5a0c18cd8fbfdca5def1d998dd5625a97 100644
--- a/cc/surfaces/surface.cc
+++ b/cc/surfaces/surface.cc
@@ -73,13 +73,6 @@ void Surface::QueueFrame(CompositorFrame frame, const DrawCallback& callback) {
     // Ask the surface manager to inform |this| when its dependencies are
     // resolved.
     factory_->manager()->RequestSurfaceResolution(this);
-
-    // We do not have to notify observers that referenced surfaces have changed
-    // in the else case because ActivateFrame will notify observers.
-    for (auto& observer : observers_) {
-      observer.OnReferencedSurfacesChanged(this, active_referenced_surfaces(),
-                                           pending_referenced_surfaces());
-    }
   } else {
     // If there are no blockers, then immediately activate the frame.
     ActivateFrame(std::move(frame));
@@ -197,11 +190,6 @@ void Surface::ActivateFrame(CompositorFrame frame) {
 
   for (auto& observer : observers_)
     observer.OnSurfaceActivated(this);
-
-  for (auto& observer : observers_) {
-    observer.OnReferencedSurfacesChanged(this, active_referenced_surfaces(),
-                                         pending_referenced_surfaces());
-  }
 }
 
 void Surface::UpdateBlockingSurfaces(