Update Windows UI on system color changes.

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index 7f037744e566069da7994d5110b385297df78335..87f702dde0eb1e8563b411c38965035bfb42ce4d 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -12,11 +12,13 @@
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
+#include "base/scoped_observer.h"
 #include "ui/aura/window_layer_type.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/events/event_source.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/rect.h"
+#include "ui/native_theme/native_theme_observer.h"
 #include "ui/views/focus/focus_manager.h"
 #include "ui/views/widget/native_widget_delegate.h"
 #include "ui/views/window/client_view.h"
@@ -95,7 +97,8 @@ class RootView;
 //
 class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
                             public ui::EventSource,
-                            public FocusTraversable {
+                            public FocusTraversable,
+                            public ui::NativeThemeObserver {
  public:
   typedef std::set<Widget*> Widgets;
 
@@ -761,6 +764,9 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   virtual FocusTraversable* GetFocusTraversableParent() OVERRIDE;
   virtual View* GetFocusTraversableParentView() OVERRIDE;
 
+  // Overridden from ui::NativeThemeObserver:
+  virtual void OnNativeThemeUpdated(ui::NativeTheme* observed_theme) OVERRIDE;
+
  protected:
   // Creates the RootView to be used within this Widget. Subclasses may override
   // to create custom RootViews that do specialized event processing.
@@ -906,6 +912,8 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // disabled.
   bool movement_disabled_;
 
+  ScopedObserver<ui::NativeTheme, ui::NativeThemeObserver> observer_manager_;
+
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };