chromium/android_webview/test/shell/assets/visual_state_during_fullscreen_test.html

<html>
<head>
<script>
  function enterFullscreen() {
    var div = document.getElementById("mydiv");
    div.webkitRequestFullScreen();
    div.addEventListener("webkitfullscreenchange", function(){
      div.style.height = "100%";
      div.style.width = "100%";
      div.style.backgroundColor = "red";
      jsObserver.notifyJava();
    });
  }
</script>
<style>
  body {
    margin: 0px;
    padding: 0px;
  }
  #enterFullscreenControl {
    height: 100%;
    width: 100%;
    padding: 0px 0px;
    background-color: blue;
  }
</style>
</head>
<body>
<button id="enterFullscreenControl" autofocus onclick="enterFullscreen(); return false">
<div id="mydiv"></div>
</button>
</body>
</html>