Enable iOS AppRTCDemo send side BWE.

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 18 matching lines @@
           'type': 'static_library',
           'includes': [ '../build/objc_common.gypi' ],
           'dependencies': [
             'rtc_base',
           ],
           'sources': [
             'objc/NSString+StdString.h',
             'objc/NSString+StdString.mm',
             'objc/RTCDispatcher.h',
             'objc/RTCDispatcher.m',
+            'objc/RTCFieldTrials.h',
+            'objc/RTCFieldTrials.mm',
             'objc/RTCFileLogger.h',
             'objc/RTCFileLogger.mm',
             'objc/RTCLogging.h',
             'objc/RTCLogging.mm',
             'objc/RTCMacros.h',
             'objc/RTCSSLAdapter.h',
             'objc/RTCSSLAdapter.mm',
             'objc/RTCTracing.h',
             'objc/RTCTracing.mm',
           ],
@@ skipping 695 matching lines @@
     },
     {
      'target_name': 'gtest_prod',
       'type': 'static_library',
       'sources': [
         'gtest_prod_util.h',
       ],
     },
   ],
 }