Adding OnReceivedOverhead to AudioEncoder.

webrtc/modules/audio_coding/codecs/audio_encoder.h

Index: webrtc/modules/audio_coding/codecs/audio_encoder.h
diff --git a/webrtc/modules/audio_coding/codecs/audio_encoder.h b/webrtc/modules/audio_coding/codecs/audio_encoder.h
index c913765fe48fd87ddc9fd45c7eb534dee016c014..8584683576a93bc950e1c6c42978edf74ca0f7ed 100644
--- a/webrtc/modules/audio_coding/codecs/audio_encoder.h
+++ b/webrtc/modules/audio_coding/codecs/audio_encoder.h
@@ -181,6 +181,13 @@ class AudioEncoder {
   // Provides RTT to this encoder to allow it to adapt.
   virtual void OnReceivedRtt(int rtt_ms);
 
+  // Provides overhead to this encoder to adapt. The overhead is the number of
+  // bytes that will be add to each payload the encoder generates. With this

[kwiberg-webrtc, 2016/12/03 00:30:56]

"add" -> "added"

And maybe "payload" -> "packet"?

[minyue-webrtc, 2016/12/06 09:04:19]

Done.

+  // and the total bandwidth and target bitrate provided by
+  // |OnReceivedUplinkBandwidth| and |OnReceivedTargetAudioBitrate|
+  // respectively, the encoder can decide its frame length and payload rate.

[kwiberg-webrtc, 2016/12/03 00:30:56]

Aren't the round-trip time and the packet loss rate relevant too? Maybe it's
best to just say "together with the other run-time parameters", or perhaps drop
this sentence altogether?

[minyue-webrtc, 2016/12/06 09:04:19]

Round trip time is not taken into account right now, but yet, I like to make the
description generalized. With that we need to say "together with the other
run-time parameters, the encoder can decide its encoding mode." This is
redundant given that we put "Provides overhead to this encoder to adapt" as the
first sentence already. So dropping this sentence is best. 

[kwiberg-webrtc, 2016/12/06 09:43:25]

Acknowledged.

+  virtual void OnReceivedOverhead(size_t overhead_bytes_per_packet);
+
   // To allow encoder to adapt its frame length, it must be provided the frame
   // length range that receivers can accept.
   virtual void SetReceiverFrameLengthRange(int min_frame_length_ms,