Pass network config constraint as base64 to avoid mangling bytes

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCMediaConstraints.h

Index: webrtc/sdk/objc/Framework/Headers/WebRTC/RTCMediaConstraints.h
diff --git a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCMediaConstraints.h b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCMediaConstraints.h
index b58fa3e74c8a4229d84d28c255ed0e2f858474db..d57231542d9d07372978f316eff43738c184137a 100644
--- a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCMediaConstraints.h
+++ b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCMediaConstraints.h
@@ -23,6 +23,10 @@ RTC_EXTERN NSString * const kRTCMediaConstraintsMinHeight;
 RTC_EXTERN NSString * const kRTCMediaConstraintsMaxFrameRate;
 RTC_EXTERN NSString * const kRTCMediaConstraintsMinFrameRate;
 RTC_EXTERN NSString * const kRTCMediaConstraintsLevelControl;
+/** The value for this key should be a base64 encoded string containing
+ *  the data from the serialized configuration proto.
+ */
+RTC_EXTERN NSString * const kRTCMediaConstraintsAudioNetworkAdaptorConfig;
 
 RTC_EXTERN NSString * const kRTCMediaConstraintsValueTrue;
 RTC_EXTERN NSString * const kRTCMediaConstraintsValueFalse;