Extract iOS SDK helpers to separate target.

webrtc/sdk/BUILD.gn

 # Copyright 2016 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("../webrtc.gni")
 if (is_ios) {
   import("//build/config/ios/rules.gni")
 }
 
 group("sdk") {
   if (is_ios) {
     public_deps = [
       ":rtc_sdk_framework_objc",
     ]
   }
 }
 
 if (is_ios || is_mac) {
   config("rtc_sdk_common_objc_config") {
     include_dirs = [
       "objc/Framework/Classes",
       "objc/Framework/Headers",
     ]
   }
 
+  rtc_static_library("rtc_sdk_helpers_objc") {
+    sources = [
+      "objc/Framework/Classes/helpers.h",
+      "objc/Framework/Classes/helpers.mm",
+    ]
+    deps = [
+      "../base:rtc_base_approved",
+    ]
+    configs += [ "..:common_objc" ]
+
+    if (is_ios) {
+      libs = [ "AVFoundation.framework" ]
+    }
+  }
+
   rtc_static_library("rtc_sdk_common_objc") {
     sources = [
       "objc/Framework/Classes/NSString+StdString.h",
       "objc/Framework/Classes/NSString+StdString.mm",
       "objc/Framework/Classes/RTCDispatcher.m",
       "objc/Framework/Classes/RTCFieldTrials.mm",
       "objc/Framework/Classes/RTCLogging.mm",
       "objc/Framework/Classes/RTCMetrics.mm",
       "objc/Framework/Classes/RTCMetricsSampleInfo+Private.h",
       "objc/Framework/Classes/RTCMetricsSampleInfo.mm",
       "objc/Framework/Classes/RTCSSLAdapter.mm",
       "objc/Framework/Classes/RTCTracing.mm",
-      "objc/Framework/Classes/helpers.h",
-      "objc/Framework/Classes/helpers.mm",
       "objc/Framework/Headers/WebRTC/RTCDispatcher.h",
       "objc/Framework/Headers/WebRTC/RTCFieldTrials.h",
       "objc/Framework/Headers/WebRTC/RTCLogging.h",
       "objc/Framework/Headers/WebRTC/RTCMacros.h",
       "objc/Framework/Headers/WebRTC/RTCMetrics.h",
       "objc/Framework/Headers/WebRTC/RTCMetricsSampleInfo.h",
       "objc/Framework/Headers/WebRTC/RTCSSLAdapter.h",
       "objc/Framework/Headers/WebRTC/RTCTracing.h",
     ]
     deps = [
+      ":rtc_sdk_helpers_objc",
       "../base:rtc_base",
     ]
     configs += [ "..:common_objc" ]
 
     public_configs = [ ":rtc_sdk_common_objc_config" ]
     if (is_ios) {
       sources += [
         "objc/Framework/Classes/RTCCameraPreviewView.m",
         "objc/Framework/Classes/RTCUIApplication.h",
         "objc/Framework/Classes/RTCUIApplication.mm",
@@ skipping 387 matching lines @@
       deps += [ "$rtc_libyuv_dir" ]
       public_deps = [
         "$rtc_libyuv_dir",
       ]
     } else {
       # Need to add a directory normally exported by libyuv.
       include_dirs = [ "$rtc_libyuv_dir/include" ]
     }
   }
 }