Fix Gn Untracked headers in webrtc/common_audio

modules/audio_coding/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.
 
 import("../../webrtc.gni")
 import("audio_coding.gni")
@@ skipping 2184 matching lines @@
       ":pcm16b",
       ":red",
       ":rent_a_codec",
       ":webrtc_opus",
       "..:module_api",
       "../..:webrtc_common",
       "../../api/audio_codecs:audio_codecs_api",
       "../../api/audio_codecs:builtin_audio_decoder_factory",
       "../../api/audio_codecs:builtin_audio_encoder_factory",
       "../../common_audio",
+      "../../common_audio:mock_common_audio",
       "../../rtc_base:protobuf_utils",
       "../../rtc_base:rtc_base",
       "../../rtc_base:rtc_base_approved",
       "../../rtc_base:rtc_base_tests_utils",
       "../../system_wrappers:system_wrappers",
       "../../test:audio_codec_mocks",
       "../../test:field_trial",
       "../../test:rtp_test_utils",
       "../../test:test_common",
       "../../test:test_support",
@@ skipping 58 matching lines @@
 # webrtc/api/audio_codecs:builtin_audio_decoder_factory instead.
 # TODO(ossu): Remove this.
 rtc_source_set("builtin_audio_encoder_factory") {
   sources = [
     "codecs/builtin_audio_encoder_factory.h",
   ]
   deps = [
     "../../api/audio_codecs:builtin_audio_encoder_factory",
   ]
 }