cancel overlay-scrollbar hover state when moving pointer out of window for ChromeOS

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 4aa0886dfb80d80425acf157f5d0e7d8daf1e872..d6c95117dd2bb45c54703c68b291ddc95097a28e 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -3266,6 +3266,16 @@ void LayerTreeHostImpl::MouseMoveAt(const gfx::Point& viewport_point) {
                                          active_tree_->device_scale_factor());
 }
 
+void LayerTreeHostImpl::MouseLeave() {
+  ScrollbarAnimationController* animation_controller =

[bokan, 2016/10/04 20:57:41]

What if the mouse isn't over the scrollbar though, rather near it when the mouse
leaves the window. This can happen if the mouse moves really quickly or if
there's a DIV whose scrollbars are showing. (DIVs do work, but only if they're
composited. To test, try running with the
--enable-prefer-compositing-to-lcd-text flag, that should enable animated
scrollbars on most DIVs and IFrames.

[chaopeng, 2016/10/05 02:29:29]

Yes, It doesnot work for near-moveout. I add a new patch for this. PTAL. Thank
you.

+      ScrollbarAnimationControllerForId(
+        scroll_layer_id_when_mouse_over_scrollbar_);
+
+  if (animation_controller) {

[dtapuska, 2016/10/04 20:50:22]

don't think you need the scope brackets :-)

+    animation_controller->DidMouseLeave();
+  }
+}
+
 void LayerTreeHostImpl::HandleMouseOverScrollbar(LayerImpl* layer_impl) {
   int new_id = Layer::INVALID_ID;
   if (layer_impl && layer_impl->ToScrollbarLayer())