Add AudioEncoder::GetTargetBitrate

webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.cc

Index: webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.cc
diff --git a/webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.cc b/webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.cc
index 66d24650a659d9b505dca51cdff39b0527bac6e2..8dc9bdf4bdd06e94305b24d441665e5a81f1b54b 100644
--- a/webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.cc
+++ b/webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.cc
@@ -66,6 +66,19 @@ int AudioEncoderIlbc::Max10MsFramesInAPacket() const {
   return num_10ms_frames_per_packet_;
 }
 
+int AudioEncoderIlbc::GetTargetBitrate() const {
+  switch (num_10ms_frames_per_packet_) {
+    case 2: case 4:
+      // 38 bytes per frame of 20 ms => 15200 bits/s.
+      return 15200;
+    case 3: case 6:
+      // 50 bytes per frame of 30 ms => (approx) 13333 bits/s.
+      return 13333;
+    default:
+      FATAL();
+  }
+}
+
 AudioEncoder::EncodedInfo AudioEncoderIlbc::EncodeInternal(
     uint32_t rtp_timestamp,
     const int16_t* audio,