Android geckoview show blank white

Question

I'm using Geckoview. It shows me white page. I'm using below tutorial:
https://www.raywenderlich.com/1381698-android-tutorial-for-geckoview-getting-started .
Also i have below log in console:

    construct@chrome://global/content/elements/browser-custom-element.js:1231:38
    connectedCallback@chrome://global/content/elements/browser-custom-element.js:381:12
    init@chrome://geckoview/content/geckoview.js:69:37
    startup@chrome://geckoview/content/geckoview.js:449:17
E/GeckoConsole: [JavaScript Error: "TypeError: this.messageManager is null" {file: "chrome://geckoview/content/geckoview.js" line: 77}]
    init@chrome://geckoview/content/geckoview.js:77:5
    startup@chrome://geckoview/content/geckoview.js:449:17

E/Gecko: ShmemAndroid::Create():open: Permission denied (13)
E/Gecko: ShmemAndroid::Map(): Bad file descriptor (9)

E/GeckoConsole: [JavaScript Error: "TypeError: this._manager.messageManager is null" {file: "chrome://geckoview/content/geckoview.js" line: 358}]
    _loadFrameScript@chrome://geckoview/content/geckoview.js:358:5
    set enabled@chrome://geckoview/content/geckoview.js:391:12
    onEvent@chrome://geckoview/content/geckoview.js:218:11
E/GeckoConsole: [JavaScript Error: "undefined"]