CodecManager: Eliminate the stereo_send_ member

webrtc/modules/audio_coding/main/acm2/codec_manager.h

Index: webrtc/modules/audio_coding/main/acm2/codec_manager.h
diff --git a/webrtc/modules/audio_coding/main/acm2/codec_manager.h b/webrtc/modules/audio_coding/main/acm2/codec_manager.h
index 00414dce970b15cd0d2920d30fce9d1f1beef616..395e88f7f191f8fb7b40a7f9a891cdade3af920a 100644
--- a/webrtc/modules/audio_coding/main/acm2/codec_manager.h
+++ b/webrtc/modules/audio_coding/main/acm2/codec_manager.h
@@ -53,8 +53,6 @@ class CodecManager final {
   // null.
   AudioDecoder* GetAudioDecoder(const CodecInst& codec);
 
-  bool stereo_send() const { return stereo_send_; }
-
   bool red_enabled() const { return red_enabled_; }
 
   bool codec_fec_enabled() const { return codec_fec_enabled_; }
@@ -75,7 +73,6 @@ class CodecManager final {
   uint8_t cng_swb_pltype_;
   uint8_t cng_fb_pltype_;
   uint8_t red_nb_pltype_;
-  bool stereo_send_;
   bool dtx_enabled_;
   ACMVADMode vad_mode_;
   CodecInst send_codec_inst_;