Rearrange dependency to enable adding finch experiment in webrtc

third_party/libjingle/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 
 # From third_party/libjingle/libjingle.gyp's target_defaults.
 config("jingle_unexported_configs") {
   defines = [
@@ skipping 238 matching lines @@
     "//third_party/webrtc/base:rtc_base",
     ":libjingle_p2p_constants",
   ]
 
   # From libjingle_common.gypi's conditions list.
   if (is_win) {
     cflags = [ "/wd4005" ]
   }
 
   if (is_nacl) {
-    deps += [ "//native_client_sdk/src/libraries/nacl_io" ]
+    # For NACL, we have to add a default implementation for field_trail.
+    deps += [
+      "//native_client_sdk/src/libraries/nacl_io",
+      "//third_party/webrtc/system_wrappers:field_trial_default",
+    ]
+  } else {
+    # Otherwise, we just add the field_trial which redirects to base.
+    sources += [ "overrides/field_trial.cc" ]
   }
 
   configs += [ ":jingle_unexported_configs" ]
   public_configs = [ ":jingle_public_configs" ]
   all_dependent_configs = [ ":jingle_all_dependent_configs" ]
 }
 
 # This has to be is a separate project due to a bug in MSVS 2008 and the
 # current toolset on android.  The problem is that we have two files named
 # "constants.cc" and MSVS/android doesn't handle this properly.
@@ skipping 231 matching lines @@
       "$p2p_dir/stunprober/stunprober.cc",
     ]
 
     deps = [
       "//third_party/webrtc/base:rtc_base",
       ":libjingle_webrtc_common",
     ]
   }
 }  # enable_webrtc
 # TODO(GYP): Port libjingle.gyp's enable_webrtc condition block.