[Mac/GN] Set up the component build.

chrome/app_shim/BUILD.gn

 # Copyright 2015 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/mac/rules.gni")
 import("//build/mac/tweak_info_plist.gni")
 import("//build/util/branding.gni")
 
 # This is the part of the shim process compiled into Chrome. It runs only
 # in the shim process, after the shim finds and loads the Chrome
@@ skipping 26 matching lines @@
 
   sources = [
     "app_mode_loader_mac.mm",
   ]
 
   deps = [
     "//chrome/common:app_mode_app_support",
   ]
 
   libs = [
+    "AppKit.framework",
     "CoreFoundation.framework",
     "Foundation.framework",
   ]
 }