[mus]Add FrameGenerator::SetHighContrastMode(bool)

services/ui/ws/display_manager.h

Index: services/ui/ws/display_manager.h
diff --git a/services/ui/ws/display_manager.h b/services/ui/ws/display_manager.h
index 0f240258379227d88c12d43f3be6bebd318b60b8..7f464b0ebcaad99419e67bd1de54f2eed03d43fe 100644
--- a/services/ui/ws/display_manager.h
+++ b/services/ui/ws/display_manager.h
@@ -81,6 +81,9 @@ class DisplayManager : public UserIdTrackerObserver,
   // Called when the AcceleratedWidget is available for |display|.
   void OnDisplayAcceleratedWidgetAvailable(Display* display);
 
+  // Switch the high contrast mode of all Displays to |enabled|.
+  void SetHighContrastMode(bool enabled);
+
  private:
   // UserIdTrackerObserver:
   void OnActiveUserIdChanged(const UserId& previously_active_id,