Wire up x-google-{min,start,max}-bitrate to WebRtcVoiceMediaChannel.

webrtc/media/engine/webrtcvoiceengine.h

Index: webrtc/media/engine/webrtcvoiceengine.h
diff --git a/webrtc/media/engine/webrtcvoiceengine.h b/webrtc/media/engine/webrtcvoiceengine.h
index 03b493744b857f903cbb09f530794787466e7b8f..76463739e81e78b7730b579678419df085d509b9 100644
--- a/webrtc/media/engine/webrtcvoiceengine.h
+++ b/webrtc/media/engine/webrtcvoiceengine.h
@@ -259,6 +259,7 @@ class WebRtcVoiceMediaChannel final : public VoiceMediaChannel,
   bool playout_ = false;
   bool send_ = false;
   webrtc::Call* const call_ = nullptr;
+  webrtc::Call::Config::BitrateConfig bitrate_config_;
 
   // SSRC of unsignalled receive stream, or -1 if there isn't one.
   int64_t default_recv_ssrc_ = -1;
@@ -280,6 +281,7 @@ class WebRtcVoiceMediaChannel final : public VoiceMediaChannel,
   std::vector<webrtc::RtpExtension> recv_rtp_extensions_;
 
   webrtc::AudioSendStream::Config::SendCodecSpec send_codec_spec_;
+  bool send_codec_spec_set_ = false;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(WebRtcVoiceMediaChannel);
 };