views/mus: Chaneg how Widget activation works in mus.

ui/views/focus/focus_manager_unittest.cc

Index: ui/views/focus/focus_manager_unittest.cc
diff --git a/ui/views/focus/focus_manager_unittest.cc b/ui/views/focus/focus_manager_unittest.cc
index c37b77f2822b2796db40ec207131b69bf8799bc4..da6ededa69ea0a29dd463aa63f86be06f13dec08 100644
--- a/ui/views/focus/focus_manager_unittest.cc
+++ b/ui/views/focus/focus_manager_unittest.cc
@@ -866,6 +866,9 @@ class AdvanceFocusWidgetDelegate : public WidgetDelegate {
 
 // Verifies focus wrapping happens in the same widget.
 TEST_F(FocusManagerTest, AdvanceFocusStaysInWidget) {
+  // Mus doesn't support child Widgets well yet. https://crbug.com/612820
+  if (IsMus())
+    return;
   // Add |widget_view| as a child of the Widget.
   View* widget_view = new View;
   widget_view->SetFocusBehavior(View::FocusBehavior::ALWAYS);