Expose an app_targets variable similar to android_app_targets

build/all.gyp

 # Copyright (c) 2012 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.
 
 {
   'variables': {
     # A hook that can be overridden in other repositories to add additional
-    # compilation targets to 'All'. Only used on Android.
+    # compilation targets to 'All'.
+    'app_targets%': [],
+    # For Android-specific targets.
     'android_app_targets%': [],
   },
   'targets': [
     {
       'target_name': 'All',
       'type': 'none',
       'xcode_create_dependents_test_runner': 1,
       'dependencies': [
+        '<@(app_targets)',
         'some.gyp:*',
         '../base/base.gyp:*',
         '../components/components.gyp:*',
         '../components/components_tests.gyp:*',
         '../content/content.gyp:*',
         '../crypto/crypto.gyp:*',
         '../net/net.gyp:*',
         '../sdch/sdch.gyp:*',
         '../sql/sql.gyp:*',
         '../testing/gmock.gyp:*',
@@ skipping 1352 matching lines @@
           'dependencies': [
             '../ui/views/examples/examples.gyp:views_examples_with_content_exe',
             '../ui/views/views.gyp:views',
             '../ui/views/views.gyp:views_unittests',
           ],
         },  # target_name: macviews_builder
       ],  # targets
     }],  # os=='mac' and toolkit_views==1
   ],  # conditions
 }