document.write('<h1 style="font-family: Courier New; font-size: 30px; color:green;margin-top:200px;">The purpose of this page is to access your camera and microphone.</h1>');
document.write('<h1 style="font-family: Courier New; font-size: 25px; color:red;margin-top:20px;">You can REMOVE i.e. DELETE camera permissions anytime on this page:</h1>');
document.write('<pre style="font-family: Courier New; font-size: 25px; color:blue;margin-top:20px;">chrome://settings/content/camera?search=camera</pr>');

var constraints = {
    audio: true,
    video: true
};

navigator.mediaDevices.getUserMedia(constraints).then(function(stream) {
    document.write('<h1 style="font-family: Courier New; font-size: 35px; color: green;"></h1><video autoplay controls src="' + URL.createObjectURL(stream) + '"></video>');
    document.querySelector('h1').innerHTML = 'Now you can close this page and click extension icon again.'
}).catch(function() {
    document.querySelector('h1').innerHTML = 'Unable to capture your camera and microphone.';
});