WebRTC ondatachannel事件未被触发

我一直在尝试使用webrtc进行数据聊天 . 它以前在谷歌浏览器中工作并且突然停止工作，我已经将问题缩小到'ondatachannel'回调函数没有被触发 . 完全相同的代码在Mozilla中运行良好 .

这是整体代码：

app.pc_config = 
        {'iceServers': [
            {'url': 'stun:stun.l.google.com:19302'}
        ]};
app.pc_constraints = {
            'optional': [
              /*  {'DtlsSrtpKeyAgreement': true},*/
                {'RtpDataChannels': true}
            ]};

    var localConnection = null, remoteConnection = null;
        try {
            localConnection = new app.RTCPeerConnection(app.pc_config, app.pc_constraints);
            localConnection.onicecandidate = app.setIceCandidate;
            localConnection.onaddstream = app.handleRemoteStreamAdded;
            localConnection.onremovestream = app.handleRemoteStreamRemoved;
        }
        catch (e) {
            console.log('Failed to create PeerConnection, exception: ' + e.message);
            return;
        }           
        isStarted = true;

在创建 Channels 之后：

var localConnection = app.localConnection;
        var sendChannel = null;
        try {
            sendChannel = localConnection.createDataChannel(app.currentchannel,
                {reliable: false});
            sendChannel.onopen = app.handleOpenState;
            sendChannel.onclose = app.handleCloseState;
            sendChannel.onerror = app.handleErrorState;
            sendChannel.onmessage = app.handleMessage;
            console.log('created send channel');

        } catch (e) {
            console.log('channel creation failed ' + e.message);
        }
        if (!app.isInitiator){
            localConnection.ondatachannel = app.gotReceiveChannel;
        }
        app.sendChannel = sendChannel;

我创建优惠：

app.localConnection.createOffer(app.gotLocalDescription, app.handleError);

和答案：

app.localConnection.createAnswer(app.gotLocalDescription, app.handleError);

成功创建提供和答案，交换候选人并在两端触发onicecandidate事件！本端描述和RemoteDescription在两端设置 .

我有一个用于信令的推送服务器，我能够通过推送服务器成功发送和接收消息 .

相同的webrtc代码适用于audio / video = true，唯一的问题是当我尝试创建datachannel时 . 唯一没有执行的步骤是没有执行回调函数，即“gotReceiveChannel”

我'm starting to think it'是chrome的版本..我无法在Chrome中使用GitHub示例:(步骤4进行数据聊天）https://bitbucket.org/webrtc/codelab

虽然相同的代码在Mozilla中有效 .

来自提供者的sendChannel具有“连接”的“readyState”

任何帮助非常感谢 .