Retain references to surfaces from both active AND pending CompositorFrames

cc/surfaces/surface.cc

Index: cc/surfaces/surface.cc
diff --git a/cc/surfaces/surface.cc b/cc/surfaces/surface.cc
index 57e3a3c98f3c47e4a35a5256a168900be8d0794b..9f6fe7358b03fcc23f07aa6f8b9cbd5f8ea06e15 100644
--- a/cc/surfaces/surface.cc
+++ b/cc/surfaces/surface.cc
@@ -63,6 +63,8 @@ void Surface::QueueFrame(CompositorFrame frame, const DrawCallback& callback) {
     pending_frame_ = std::move(frame);
     if (pending_frame_) {
       factory_->ReceiveFromChild(pending_frame_->resource_list);
+      pending_referenced_surfaces_ =
+          pending_frame_->metadata.referenced_surfaces;
       // Ask the surface manager to inform |this| when its dependencies are
       // resolved.
       factory_->manager()->RequestSurfaceResolution(this);
@@ -149,6 +151,7 @@ void Surface::ActivatePendingFrame() {
   DCHECK(pending_frame_);
   ActivateFrame(std::move(pending_frame_.value()));
   pending_frame_.reset();
+  pending_referenced_surfaces_.clear();
   // ActiveFrame resources are now double ref-ed. Unref.
   UnrefFrameResources(*active_frame_);
 }