NetEq: Fix a bug in expand_rate and speech_expand_rate calculation

webrtc/modules/audio_coding/neteq/merge.cc

Index: webrtc/modules/audio_coding/neteq/merge.cc
diff --git a/webrtc/modules/audio_coding/neteq/merge.cc b/webrtc/modules/audio_coding/neteq/merge.cc
index d50b66588a8d2e146905ea47a83a55bb4a2ada31..8662569cfe713f1b9fa2f9184ec8681c5ff0fe05 100644
--- a/webrtc/modules/audio_coding/neteq/merge.cc
+++ b/webrtc/modules/audio_coding/neteq/merge.cc
@@ -154,7 +154,10 @@ size_t Merge::Process(int16_t* input, size_t input_length,
   // Copy back the first part of the data to |sync_buffer_| and remove it from
   // |output|.
   sync_buffer_->ReplaceAtIndex(*output, old_length, sync_buffer_->next_index());
+  RTC_DCHECK_EQ(output_length, output->Size());

[minyue-webrtc, 2017/05/05 07:14:00]

I don't quite see how this relates to the changes in stats.

[hlundin-webrtc, 2017/05/05 07:42:14]

I basically just wanted to make sure that the return value from this function
would never go negative (which would cause a wrap). I'll reduce to a single
DCHECK.

[minyue-webrtc, 2017/05/05 07:50:39]

Acknowledged.

+  RTC_DCHECK_GE(output_length, old_length);
   output->PopFront(old_length);
+  RTC_DCHECK_EQ(output_length - old_length, output->Size());
 
   // Return new added length. |old_length| samples were borrowed from
   // |sync_buffer_|.