Implement all system menu title row buttons for Ash MD

ash/common/system/tray/system_menu_button.cc

Index: ash/common/system/tray/system_menu_button.cc
diff --git a/ash/common/system/tray/system_menu_button.cc b/ash/common/system/tray/system_menu_button.cc
index 3ac437d6e40a3cf517917011f5d41a760a5b0095..091441920a39416251d0b0b576246d3372959d50 100644
--- a/ash/common/system/tray/system_menu_button.cc
+++ b/ash/common/system/tray/system_menu_button.cc
@@ -22,6 +22,10 @@ SystemMenuButton::SystemMenuButton(views::ButtonListener* listener,
     : views::ImageButton(listener) {
   gfx::ImageSkia image = gfx::CreateVectorIcon(icon, kMenuIconColor);
   SetImage(views::Button::STATE_NORMAL, &image);
+  gfx::ImageSkia disabled_image =
+      gfx::CreateVectorIcon(icon, kMenuIconColorDisabled);
+  SetImage(views::Button::STATE_DISABLED, &disabled_image);
+
   const int horizontal_padding = (kMenuButtonSize - image.width()) / 2;
   const int vertical_padding = (kMenuButtonSize - image.height()) / 2;
   SetBorder(