Reland of Moving webrtc.gni up one level from build/

webrtc/modules/BUILD.gn

 # Copyright (c) 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("../build/webrtc.gni")
+import("../webrtc.gni")
 import("audio_coding/audio_coding.gni")
 
 group("modules") {
   public_deps = [
     "audio_coding",
     "audio_conference_mixer",
     "audio_device",
     "audio_mixer",
     "audio_processing",
     "bitrate_controller",
@@ skipping 299 matching lines @@
       "../test:test_common",
       "../test:test_main",
       "remote_bitrate_estimator:bwe_simulator_lib",
       "video_capture",
       "//testing/gmock",
       "//testing/gtest",
       "//third_party/gflags",
     ]
   }
 }