Chrome OS: adjust wifi icons.

ash/system/tray/tray_popup_item_style.h

Index: ash/system/tray/tray_popup_item_style.h
diff --git a/ash/system/tray/tray_popup_item_style.h b/ash/system/tray/tray_popup_item_style.h
index a58fb020ad9187d66b5ba9f96605c482d373a625..8d1c5dc80b326315f44b1a31e3b8cbf964a6fd11 100644
--- a/ash/system/tray/tray_popup_item_style.h
+++ b/ash/system/tray/tray_popup_item_style.h
@@ -50,6 +50,8 @@ class TrayPopupItemStyle {
     CAPTION,
   };
 
+  static constexpr double kInactiveIconAlpha = 0.54;
+
   static SkColor GetIconColor(ColorStyle color_style);
 
   explicit TrayPopupItemStyle(FontStyle font_style);