Move ios_helpers to sdk folder

webrtc/modules/audio_device/BUILD.gn

 # 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.
 
 import("../../build/webrtc.gni")
 
@@ skipping 164 matching lines @@
       if (is_ios) {
         public_deps = [
           "../../base:rtc_base",
           "../../sdk:rtc_sdk_common_objc",
         ]
         sources += [
           "ios/audio_device_ios.h",
           "ios/audio_device_ios.mm",
           "ios/audio_device_not_implemented_ios.mm",
           "ios/audio_session_observer.h",
-          "ios/helpers_ios.h",
-          "ios/helpers_ios.mm",
           "ios/objc/RTCAudioSession+Configuration.mm",
           "ios/objc/RTCAudioSession+Private.h",
           "ios/objc/RTCAudioSession.h",
           "ios/objc/RTCAudioSession.mm",
           "ios/objc/RTCAudioSessionConfiguration.h",
           "ios/objc/RTCAudioSessionConfiguration.m",
           "ios/objc/RTCAudioSessionDelegateAdapter.h",
           "ios/objc/RTCAudioSessionDelegateAdapter.mm",
           "ios/voice_processing_audio_unit.h",
           "ios/voice_processing_audio_unit.mm",
@@ skipping 94 matching lines @@
       "../../system_wrappers",
       "../../test:test_main",
       "../../test:test_support",
       "../rtp_rtcp",
       "../utility",
       "//testing/gtest",
     ]
     public_configs = [ ":audio_device_config" ]
   }
 }