Decoupling rtc_base from apple specific code [without cyclic deps]

webrtc/rtc_tools/network_tester/BUILD.gn

 # Copyright (c) 2017 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")
 import("//third_party/protobuf/proto_library.gni")
@@ skipping 100 matching lines @@
     ]
 
     deps = [
       ":network_tester",
     ]
 
     if (!build_with_chromium && is_clang) {
       # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
       suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
     }
+
+    if (is_ios || is_mac) {
+      deps += [ "../../rtc_base:rtc_base_apple" ]
+    }
   }
 }
 
 if (is_android) {
   android_apk("NetworkTesterMobile") {
     testonly = true
     apk_name = "NetworkTesterMobile"
     android_manifest = "androidapp/AndroidManifest.xml"
 
     deps = [
@@ skipping 36 matching lines @@
       ":network_tester",
       "../../system_wrappers:field_trial_default",
     ]
 
     suppressed_configs += [ "//build/config/android:hide_all_but_jni_onload" ]
     configs += [ "//build/config/android:hide_all_but_jni" ]
 
     output_extension = "so"
   }
 }