constructor(inputStream, debugPath) {
    /**
     * @private @const {!RTCPeerConnection} the calling side of the peer
     *     connection, connected to inputStream_.
     */
    this.caller_ = new RTCPeerConnection(null);
    /**
     * @private @const {!RTCPeerConnection} the answering side of the peer
     *     connection, providing the stream returned by getMediaStream.
     */
    this.callee_ = new RTCPeerConnection(null);
    /** @private {string} */
    this.debugPath_ = debugPath;
    /**
     * @private @const {!Promise<!MediaStream>} the stream containing tracks
     *     from callee_, returned by getMediaStream.
     */
    this.outputStreamPromise_ = this.init_(inputStream);
  }
@param {!MediaStream} inputStream stream to pipe over the peer connection
@param {string} debugPath the path to this object from the debug global var