Update iOS AppRTCDemo to use the updated Objective-C API.

webrtc/base/base.gyp

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 42 matching lines @@
               ],
               'all_dependent_settings': {
                 'xcode_settings': {
                   'OTHER_LDFLAGS': [
                     '-framework AVFoundation',
                   ],
                 },
               },
             }],
           ],
+          'all_dependent_settings': {
+            'xcode_settings': {
+              'CLANG_ENABLE_OBJC_ARC': 'YES',
+            },
+          },
           'xcode_settings': {
             'CLANG_ENABLE_OBJC_ARC': 'YES',
             'CLANG_WARN_OBJC_MISSING_PROPERTY_SYNTHESIS': 'YES',
           },
         }
       ],
     }], # OS=="ios"
   ],
   'targets': [
     {
@@ skipping 675 matching lines @@
     },
     {
      'target_name': 'gtest_prod',
       'type': 'static_library',
       'sources': [
         'gtest_prod_util.h',
       ],
     },
   ],
 }