Revert of Remove various IDs

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.
  */
 
@@ skipping 17 matching lines @@
 using testing::_;
 using testing::Exactly;
 using testing::Invoke;
 using testing::Return;
 
 namespace webrtc {
 
 namespace {
 
 constexpr int kDefaultSampleRateHz = 48000;
+constexpr int kId = 1;
 
 // Utility function that resets the frame member variables with
 // sensible defaults.
 void ResetFrame(AudioFrame* frame) {
+  frame->id_ = kId;
   frame->sample_rate_hz_ = kDefaultSampleRateHz;
   frame->num_channels_ = 1;
 
   // Frame duration 10ms.
   frame->samples_per_channel_ = kDefaultSampleRateHz / 100;
   frame->vad_activity_ = AudioFrame::kVadActive;
   frame->speech_type_ = AudioFrame::kNormalSpeech;
 }
 
 std::string ProduceDebugText(int sample_rate_hz,
@@ skipping 482 matching lines @@
         }
 
         mixer->Mix(number_of_channels, &frame_for_mixing);
         EXPECT_EQ(rate, frame_for_mixing.sample_rate_hz_);
         EXPECT_EQ(number_of_channels, frame_for_mixing.num_channels_);
       }
     }
   }
 }
 }  // namespace webrtc