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 89035df5acb5fefdcaf9ac8ef63e2b78e05c1aca..16c34d4490a56dff9c45dec2f4d63d9ddcab03e0 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1971,6 +1971,12 @@ LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
 }
 
 void LayerTreeImpl::RegisterSelection(const LayerSelection& selection) {
+  if (selection_ == selection)
+    return;
+
+  if (IsActiveTree())
+    layer_tree_host_impl_->HandleVisibilityChanged();

[danakj, 2016/10/20 22:40:26]

I think a nicer way to frame this is to have the bool on LayerTreeImpl.

Then LTHI can query the active LayerTreeImpl to see if handle visibility
changed, instead of this informing LTHI if its the active tree.

It would require a Reset function for LTHI to call when it reads it. Maybe
GetAndReset could be combined if u want.

If LayerTreeImpl has lots of damage-generating things we could generalize this
eventually to like "get damage for tree or something" but I don't see that yet.

[amaralp, 2016/10/21 03:47:19]

Done.

[amaralp, 2016/10/21 03:47:19]

Done.

+
   selection_ = selection;
 }