Update the background color of ARC notifications when notification settings is opened.

ui/message_center/views/padded_button.cc

Index: ui/message_center/views/padded_button.cc
diff --git a/ui/message_center/views/padded_button.cc b/ui/message_center/views/padded_button.cc
index 4c73a90f41f8cfb762ecac089f4ea810351a5be5..08e3e6f16200b66dec6d653ae7bfcb30a799c1e3 100644
--- a/ui/message_center/views/padded_button.cc
+++ b/ui/message_center/views/padded_button.cc
@@ -22,8 +22,8 @@ PaddedButton::PaddedButton(views::ButtonListener* listener)
   SetFocusPainter(views::Painter::CreateSolidFocusPainter(
       kFocusBorderColor,
       gfx::Insets(1, 2, 2, 2)));
-  set_background(views::Background::CreateSolidBackground(
-      SkColorSetA(SK_ColorWHITE, 0.9 * 0xff)));
+  set_background(
+      views::Background::CreateSolidBackground(kControlButtonBackgroundColor));
   SetBorder(views::CreateEmptyBorder(gfx::Insets(kControlButtonBorderSize)));
   set_animate_on_state_change(false);