Remove various IDs

modules/audio_mixer/audio_mixer_impl_unittest.cc

Index: modules/audio_mixer/audio_mixer_impl_unittest.cc
diff --git a/modules/audio_mixer/audio_mixer_impl_unittest.cc b/modules/audio_mixer/audio_mixer_impl_unittest.cc
index 678f625eac431d8ced0317bcf8b5bf0533e1f4d5..4461e6e038dc15c42134a858652b875b4e064ec8 100644
--- a/modules/audio_mixer/audio_mixer_impl_unittest.cc
+++ b/modules/audio_mixer/audio_mixer_impl_unittest.cc
@@ -35,12 +35,10 @@ 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;