views: add focus ring to TreeView

ui/views/controls/tree/tree_view.h

Index: ui/views/controls/tree/tree_view.h
diff --git a/ui/views/controls/tree/tree_view.h b/ui/views/controls/tree/tree_view.h
index 5eb096e3d2fb4f04d33cdfb68180c05f5342992f..38bb7d425f050e9cca25dd9a7b5427b7f84d9244 100644
--- a/ui/views/controls/tree/tree_view.h
+++ b/ui/views/controls/tree/tree_view.h
@@ -24,9 +24,10 @@ class Rect;
 
 namespace views {
 
+class PrefixSelector;
+class ScrollView;
 class Textfield;
 class TreeViewController;
-class PrefixSelector;
 
 // TreeView displays hierarchical data as returned from a TreeModel. The user
 // can expand, collapse and edit the items. A Controller may be attached to
@@ -349,6 +350,10 @@ class VIEWS_EXPORT TreeView : public View,
   // control.
   bool IsPointInExpandControl(InternalNode* node, const gfx::Point& point);
 
+  // Returns the View that the focus ring for this TreeView should be drawn
+  // around.
+  ScrollView* FindFocusRingView();

[sky, 2016/10/12 23:58:01]

This function is mildly confusing as based on name I expect it to find the
FocusRing, but that isn't the case. I think either name it
GetFocusRingContainerView() or possibly GetScrollView() as that is what it does
too.

[Elly Fong-Jones, 2016/10/13 11:14:56]

It is gone now and its logic moved into TreeView::SetHasFocusRing().

+
   // The model, may be null.
   ui::TreeModel* model_;