Blink handle selection handle visibility

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index ff5da70a7e7ec633092d56de8cc7282b1316b21e..075ddfabb5c60cf92a07ff6242ac02af43a3ce24 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1931,9 +1931,14 @@ LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
 }
 
 void LayerTreeImpl::RegisterSelection(const LayerSelection& selection) {
+  selection_changed_ = selection_ != selection;

[aelias_OOO_until_Jul13, 2016/08/08 21:30:51]

This relies on RegisterSelection being called again on the next commit.  But,
there may be multiple draws between two commits, and only the first draw is
needed.  I think we should be mutating state at draw time.

The damage-tracking code clears viewport_damage_rect_ in
LayerTreeHostImpl::PrepareToDraw.  I suggest roughly imitating that pattern for
this.

[amaralp, 2016/10/14 00:53:06]

Done.

   selection_ = selection;
 }
 
+bool LayerTreeImpl::SelectionChanged() {
+  return selection_changed_;
+}
+
 static gfx::SelectionBound ComputeViewportSelectionBound(
     const LayerSelectionBound& layer_bound,
     LayerImpl* layer,