I want to use getUserMedia in Android Lolipop 5.0 WebView

I want to start a webcam using getUserMedia in Android WebView. The following wrote the code, but errorCallback is called. why not?

By the way, the following website was implemented by link.

Android, WebViews and getUserMedia: Putting It All Together

myWebView = (WebView) findViewById(R.id.webview);

// Settings
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
webSettings.setAllowFileAccessFromFileURLs(true);
webSettings.setAllowUniversalAccessFromFileURLs(true);
myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");

// Set a web view client and a chrome client
myWebView.setWebViewClient(new WebViewClient());
myWebView.setWebChromeClient(new WebChromeClient() {
  // Need to accept permissions to use the camera and audio
  @Override
  public void onPermissionRequest(final PermissionRequest request) {
    Log.d(TAG, "onPermissionRequest");
    MainActivity.this.runOnUiThread(new Runnable() {
      @TargetApi(Build.VERSION_CODES.LOLLIPOP)
      @Override
      public void run() {
        if(request.getOrigin().toString().equals(LOCAL_FILE)) {
          request.grant(request.getResources());
        } 
        else {
            request.deny();
        }
      }
    });
  }
});
// Load the local HTML file into the webview
myWebView.loadUrl(LOCAL_FILE);

      

        
        
        
      

    

[permissions]

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

      

        
        
        
      

    

[JavaScript]

 var constraints = {video: true, audio: true};
 var localStream = null;
 function init() {
    console.log(‘Getting user media with constraints’, constraints);
    navigator.webkitGetUserMedia(constraints, handleUserMediaSuccess, handleUserMediaError);
 };

 function handleUserMediaSuccess(stream) {
    console.log(‘[+] Successfully got local video stream!’);
    attachMediaStream = function(element, stream) {
          element.src = window.webkitURL.createObjectURL(stream);
    };
    attachMediaStream(document.getElementById("localVideo"), stream);
 };

 function handleUserMediaError(error) {
    alert(‘[!] getUserMedia error: ‘, error);
 };

 window.onload = function() {
    init();
 };