Implement new RPDQ copy logic for CALayer promotion.

cc/output/overlay_processor.cc

Index: cc/output/overlay_processor.cc
diff --git a/cc/output/overlay_processor.cc b/cc/output/overlay_processor.cc
index bad6f3ea1bb2dc7d98c48d6a59dfd81de3535703..7996ce6789f5c0eb20c6acb1641848028a149cfd 100644
--- a/cc/output/overlay_processor.cc
+++ b/cc/output/overlay_processor.cc
@@ -52,7 +52,6 @@ bool OverlayProcessor::ProcessForCALayers(
   // layers then clear the list and remove the backbuffer from the overcandidate
   // list.
   overlay_candidates->clear();
-  render_pass->quad_list.clear();
   overlay_damage_rect_ = render_pass->output_rect;
   *damage_rect = gfx::Rect();
   return true;