desktop-views: Create one fewer aura::Window for each widget.

ui/views/widget/desktop_aura/desktop_focus_rules.cc

Index: ui/views/widget/desktop_aura/desktop_focus_rules.cc
diff --git a/ui/views/widget/desktop_aura/desktop_focus_rules.cc b/ui/views/widget/desktop_aura/desktop_focus_rules.cc
index 1d7d40c5e3dc133ac13b6ed3628f72ea95a17d30..9f4c1bd8f40af09b83f494d4e7d776462840abdc 100644
--- a/ui/views/widget/desktop_aura/desktop_focus_rules.cc
+++ b/ui/views/widget/desktop_aura/desktop_focus_rules.cc
@@ -25,8 +25,7 @@ bool DesktopFocusRules::CanActivateWindow(aura::Window* window) const {
 bool DesktopFocusRules::SupportsChildActivation(aura::Window* window) const {
   // In Desktop-Aura, only the content_window or children of the RootWindow are
   // activatable.
-  return window == content_window_->parent() ||
-         window->GetRootWindow() == window;
+  return window->IsRootWindow();
 }
 
 bool DesktopFocusRules::IsWindowConsideredVisibleForActivation(