views: add focus ring to TreeView

ui/views/style/platform_style.cc

Index: ui/views/style/platform_style.cc
diff --git a/ui/views/style/platform_style.cc b/ui/views/style/platform_style.cc
index b586060750c0b259e6d37f8f27caf8c9a4ed2ca6..706f0ab116d87b59eedf9db05b91a8bb9a2d7df8 100644
--- a/ui/views/style/platform_style.cc
+++ b/ui/views/style/platform_style.cc
@@ -42,6 +42,7 @@ const bool PlatformStyle::kDialogDefaultButtonCanBeCancel = true;
 const bool PlatformStyle::kTextfieldDragVerticallyDragsToEnd = false;
 const CustomButton::NotifyAction PlatformStyle::kMenuNotifyActivationAction =
     CustomButton::NOTIFY_ON_RELEASE;
+const bool PlatformStyle::kTreeViewHasFocusRing = false;
 const bool PlatformStyle::kTreeViewSelectionPaintsEntireRow = false;
 const bool PlatformStyle::kUseRipples = true;