Enable a minimal content/ build on iOS

content/content_app.gypi

 # 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.
 
 {
   'include_dirs': [
     '..',
   ],
   'dependencies': [
     '../base/base.gyp:base',
@@ skipping 33 matching lines @@
         '<(SHARED_INTERMEDIATE_DIR)/content',
       ],
       'dependencies': [
         'content.gyp:content_jni_headers',
         '../skia/skia.gyp:skia',
       ],
     }],
     ['OS=="ios"', {
       'sources!': [
         'app/content_main.cc',
+        # TODO(ios): Remove this once content_main_runner builds
+        # for iOS.
+        'app/content_main_runner.cc',
       ],
     }],
   ],
 }