Move Screen, its impls, DisplayObserver and DisplayChangeNotifier to ui/display

ui/display/display_observer.cc

Index: ui/display/display_observer.cc
diff --git a/ui/gfx/display_observer.cc b/ui/display/display_observer.cc
similarity index 58%
rename from ui/gfx/display_observer.cc
rename to ui/display/display_observer.cc
index f8e3c07640164e35c05b76337238ab49eecb59cd..fb3fd8c727e3b0e6e424db792c01bc2e643b9a2a 100644
--- a/ui/gfx/display_observer.cc
+++ b/ui/display/display_observer.cc
@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ui/gfx/display_observer.h"
+#include "ui/display/display_observer.h"
 
-namespace gfx {
+namespace display {
 
-DisplayObserver::~DisplayObserver() {
-}
+DisplayObserver::~DisplayObserver() {}
 
-}  // namespace gfx
+}  // namespace display