Adding cbr support for Opus

webrtc/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc

Index: webrtc/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
diff --git a/webrtc/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc b/webrtc/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
index 3faad68db48ffd84394df8e0274fd463b78e7cef..2fddb435d19c0dab56c516c70755340f6071889b 100644
--- a/webrtc/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
+++ b/webrtc/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
@@ -103,6 +103,10 @@ bool AudioEncoderCopyRed::SetFec(bool enable) {
   return speech_encoder_->SetFec(enable);
 }
 
+bool AudioEncoderCopyRed::SetCbr(bool enable) {
+  return speech_encoder_->SetCbr(enable);
+}
+
 bool AudioEncoderCopyRed::SetDtx(bool enable) {
   return speech_encoder_->SetDtx(enable);
 }