Nativescript application dont open file chooser on WebView

I have an application Nativescript with a WebView. These WebView open a url, and this url have a input type file. When i touch in this input, nothing happens. I've trying extend the WebChromeClient class and the method onShowFileChooser is called, but nothing happens.

let myWebChromeClientClass = android.webkit.WebChromeClient.extend({
          onShowFileChooser: function (WebView, ValueCallback, FileChooserParams) {
            console.log("onShowFileChooser");
           // What i have to do here?
          }
        });
        let myWebChromeClient = new myWebChromeClientClass();
 webview.android.setWebChromeClient(myWebChromeClient);

I dont know what i have to do.

The problem is that WebView is very limited. But, you can use a plugin to call a file chooser. In my solution i used the imagepicker plugin The complete code is:

fileCallback(filePathCallback) {
        console.log("fileCallback");
        let context = imagePicker.create({
          mode: "single",
          mediaType: imagePicker.ImagePickerMediaType.Any
        });
        return this.startSelection(context, filePathCallback);
      },
      startSelection(context, filePathCallback) {
        console.log("startSelection");
        let abc = context.authorize().then(() => {
          return context.present();
        })
          .then((selection) => {
            selection.forEach((selected) => {
              let path = selected.android;
              let file = fs.File.fromPath(path);
              this.file_path = file.path;
              this.file_path = "file://" + this.file_path;
              let results = Array.create(android.net.Uri, 1);
              results[0] = android.net.Uri.parse(this.file_path);
              filePathCallback.onReceiveValue(results);
            });
          }).catch(function (e) {
            console.log(e);
          });
      }

     let TNSWebChromeClient = android.webkit.WebChromeClient.extend({
          onShowFileChooser: function (view, valueCallback, fileChooserParams) {
            console.log("onShowFileChooser");
            _this.fileCallback(valueCallback);
            return true;
          }
        });
    let thsWebChromeClient = new TNSWebChromeClient();
     webview.android.setWebChromeClient(thsWebChromeClient);