[Mac/GN] Set up the component build.

ui/message_center/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 
 # TODO(msw|mukai|dewittj): Move ash-specific files: crbug.com/585175
 component("message_center") {
@@ skipping 65 matching lines @@
       "popup_timer.cc",
       "popup_timer.h",
       "popup_timers_controller.cc",
       "popup_timers_controller.h",
     ]
 
     if (is_win) {
       deps += [ "//ui/aura" ]
     }
 
+    if (is_mac) {
+      libs = [
+        "AppKit.framework",
+        "Foundation.framework",
+      ]
+    }
+
     # On Mac, toolkit-views builds still use the Cocoa UI. Keep this in sync
     # with message_center_unittests below.
     if (toolkit_views && !is_mac) {
       sources += [
         "views/bounded_label.cc",
         "views/bounded_label.h",
         "views/constants.h",
         "views/desktop_popup_alignment_delegate.cc",
         "views/desktop_popup_alignment_delegate.h",
         "views/message_bubble_base.cc",
@@ skipping 138 matching lines @@
         # Compositor is needed by message_center_view_unittest.cc and for the
         # fonts used by bounded_label_unittest.cc.
         "//ui/compositor",
         "//ui/display",
         "//ui/views",
         "//ui/views:test_support",
       ]
     }
   }  # enable_notifications && !is_android
 }