Loosening the coupling between WebRTC and //third_party/protobuf

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 82 matching lines @@
   # if (is_freebsd) {
   #   defines += [ "FREEBSD" ]
   # }
 }
 
 config("common_config") {
   cflags = []
   cflags_cc = []
   defines = []
 
+  if (rtc_enable_protobuf) {
+    defines += [ "WEBRTC_ENABLE_PROTOBUF=1" ]
+  } else {
+    defines += [ "WEBRTC_ENABLE_PROTOBUF=0" ]
+  }
+
   if (rtc_restrict_logging) {
     defines += [ "WEBRTC_RESTRICT_LOGGING" ]
   }
 
   if (rtc_include_internal_audio_device) {
     defines += [ "WEBRTC_INCLUDE_INTERNAL_AUDIO_DEVICE" ]
   }
 
   if (rtc_relative_path) {
     defines += [ "EXPAT_RELATIVE_PATH" ]
@@ skipping 387 matching lines @@
       ]
 
       deps = [
         "//base:base_java_test_support",
         "//webrtc/examples:AppRTCMobile_javalib",
         "//webrtc/sdk/android:libjingle_peerconnection_java",
       ]
     }
   }
 }