Refactoring ./webrtc/modules/BUILD.gn for gn check

webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc

 /*
  *  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.
  */
 
 #include <string.h>
 
 #include <limits>
 #include <memory>
 #include <utility>
 
 #include "webrtc/api/audio/audio_mixer.h"
 #include "webrtc/base/bind.h"
 #include "webrtc/base/thread.h"
 #include "webrtc/modules/audio_mixer/audio_mixer_impl.h"
-#include "webrtc/modules/audio_mixer/default_output_rate_calculator.h"
 #include "webrtc/test/gmock.h"
 
 using testing::_;
 using testing::Exactly;
 using testing::Invoke;
 using testing::Return;
 
 namespace webrtc {
 
 namespace {
@@ skipping 441 matching lines @@
   constexpr int kOutputRate = 8000;
   const auto mixer = AudioMixerImpl::CreateWithOutputRateCalculator(
       std::unique_ptr<OutputRateCalculator>(
           new CustomRateCalculator(kOutputRate)));
 
   mixer->Mix(1, &frame_for_mixing);
 
   EXPECT_EQ(kOutputRate, frame_for_mixing.sample_rate_hz_);
 }
 }  // namespace webrtc