Add rtc_enable_external_auth variable for setting ENABLE_EXTERNAL_AUTH

webrtc/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.
 
 # TODO(kjellander): Rebase this to webrtc/build/common.gypi changes after r6330.
 
@@ skipping 104 matching lines @@
   }
 
   if (!rtc_libvpx_build_vp9) {
     defines += [ "RTC_DISABLE_VP9" ]
   }
 
   if (rtc_enable_sctp) {
     defines += [ "HAVE_SCTP" ]
   }
 
+  if (rtc_enable_external_auth) {
+    defines += [ "ENABLE_EXTERNAL_AUTH" ]
+  }
+
   if (build_with_chromium) {
     defines += [
       # NOTICE: Since common_inherited_config is used in public_configs for our
       # targets, there's no point including the defines in that config here.
       # TODO(kjellander): Cleanup unused ones and move defines closer to the
       # source when webrtc:4256 is completed.
-      "ENABLE_EXTERNAL_AUTH",
       "HAVE_OPENSSL_SSL_H",
       "HAVE_SRTP",
       "HAVE_WEBRTC_VIDEO",
       "HAVE_WEBRTC_VOICE",
       "LOGGING_INSIDE_WEBRTC",
       "SSL_USE_OPENSSL",
       "USE_WEBRTC_DEV_BRANCH",
     ]
   } else {
     if (is_posix) {
@@ skipping 570 matching lines @@
       ]
 
       deps = [
         "//base:base_java_test_support",
         "//webrtc/examples:AppRTCMobile_javalib",
         "//webrtc/sdk/android:libjingle_peerconnection_java",
       ]
     }
   }
 }