[Mac/GN] Add a BUILD.gn file for //chrome/app_shim.

build/config/mac/rules.gni

 # 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/base_rules.gni")
 
 # Generates Info.plist files for Mac apps and frameworks.
 #
 # Arguments
 #
@@ skipping 168 matching lines @@
     visibility = [ ":$_executable_bundle_data" ]
     forward_variables_from(invoker,
                            "*",
                            [
                              "assert_no_deps",
                              "data_deps",
                              "info_plist",
                              "output_name",
                              "visibility",
                            ])
+    if (defined(add_configs)) {
+      configs += add_configs
+    }
     output_name = _output_name
     output_dir = "$target_out_dir/$_executable_target"
   }
 
   bundle_data(_executable_bundle_data) {
     visibility = [ ":$_target_name" ]
     forward_variables_from(invoker, [ "testonly" ])
     sources = [
       "$target_out_dir/$_executable_target/$_output_name",
     ]
@@ skipping 103 matching lines @@
                            ])
     if (!defined(deps)) {
       deps = []
     }
     deps += [ ":$_loadable_module_bundle_data" ]
 
     bundle_root_dir = "$root_out_dir/$_output_name.plugin/Contents"
     bundle_executable_dir = "$bundle_root_dir/MacOS"
   }
 }