Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/media/video-capture-preview.html 

<!DOCTYPE html>
<title>Verify video play using media stream as video src.</title>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<video autoplay></video>
<script>
async_test(function(t) {
    var video = document.querySelector("video");
    navigator.webkitGetUserMedia({video:true}, function(stream) {
        video.ontimeupdate = t.step_func(function() {
            // restart preview.
            video.srcObject = stream;
            video.ontimeupdate = t.step_func_done();
        });

        //start preview.
        video.srcObject = stream;
    }, getStreamFailed);

    function getStreamFailed(error) {
        t.unreached_func();
    }

    video.onerror = t.unreached_func();
    video.onloadstart = t.step_func(function() {});
    video.onloadeddata = t.step_func(function() {});
    video.oncanplay = t.step_func(function() {});
    video.onplay = t.step_func(function() {});
    video.oncanplaythrough = t.step_func(function() {});
});
</script>