Change single-display screens to use ScreenBase and DisplayList.

ui/display/display_list.h

Index: ui/display/display_list.h
diff --git a/ui/display/display_list.h b/ui/display/display_list.h
index c280fd44b491631dcd6244d73cf96741e84a783b..0401f1c9496b3487d854ccac26d72daa35a2b605 100644
--- a/ui/display/display_list.h
+++ b/ui/display/display_list.h
@@ -56,7 +56,6 @@ class DISPLAY_EXPORT DisplayList {
   const Displays& displays() const { return displays_; }
 
   Displays::const_iterator FindDisplayById(int64_t id) const;
-  Displays::iterator FindDisplayById(int64_t id);
 
   Displays::const_iterator GetPrimaryDisplayIterator() const;
 
@@ -93,6 +92,8 @@ class DISPLAY_EXPORT DisplayList {
 
   Type GetTypeByDisplayId(int64_t display_id) const;
 
+  Displays::iterator FindDisplayByIdInternal(int64_t id);
+
   std::vector<display::Display> displays_;
   int primary_display_index_ = -1;
   base::ObserverList<display::DisplayObserver> observers_;