cc: Move copy requests from layers to the effect tree

cc/trees/occlusion_tracker.cc

Index: cc/trees/occlusion_tracker.cc
diff --git a/cc/trees/occlusion_tracker.cc b/cc/trees/occlusion_tracker.cc
index b1319b8a7a4a5fb0ac857acdd28c89c7d413d850..ba68f4e76e8c83c67769df951a02f69abdd4f397 100644
--- a/cc/trees/occlusion_tracker.cc
+++ b/cc/trees/occlusion_tracker.cc
@@ -177,7 +177,7 @@ void OcclusionTracker::FinishedRenderTarget(const LayerImpl* finished_target) {
   // Readbacks always happen on render targets so we only need to check
   // for readbacks here.
   bool target_is_only_for_copy_request =
-      finished_target->HasCopyRequest() && finished_target->IsHidden();
+      surface->HasCopyRequest() && finished_target->IsHidden();
 
   // If the occlusion within the surface can not be applied to things outside of
   // the surface's subtree, then clear the occlusion here so it won't be used.