Chrome Version       : Version 51.0.2704.42 beta (64-bit)
Platform 8172.28.0 (Official Build) beta-channel link

URLs (if applicable) : protected

Other browsers tested: Chrome OS version 50
  Add OK or FAIL, along with the version, after other browsers where you
have tested this issue:
     Safari: not tested
    Firefox: not tested
         IE: not tested

What steps will reproduce the problem?
(1) Use Chrome OS version 51 (beta) in a Chromebook.
(2) A customer's web app has an Google authorization step so create any index.html code that checks the signed in Google account and has any scopes to grant.
(3) Once approved, the following console error occurs: 
"TypeError: Cannot assign to read only property 'indexedDB' of object '#<Window>'"


What is the expected result?
passes authorization.

What happens instead?
console error: 
"TypeError: Cannot assign to read only property 'indexedDB' of object '#<Window>'"



Please provide any additional information below. Attach a screenshot if
possible.

Some example code to duplicate error with Chrome OS version 51:

var scopes = 'https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/userinfo.profile https://www.googleapis.com/auth/drive';

...
function handleClientLoad() {
    loadText = document.getElementById('loading').childNodes[1].childNodes[1];
    loadText.nodeValue = 'Checking Google authorization...';
    gapi.client.setApiKey(apiKey);
    window.setTimeout(checkAuth, 1);
}

function checkAuth() {
    gapi.auth.authorize({
        client_id: clientId,
        scope: scopes,
        immediate: true
    }, handleAuthResult);
}

function handleAuthResult(authResult) {
    $(function() {
        $loading = $('#loading');
        if (authResult && !authResult.error) {
            if ($auth) {
                $auth.hide();
                $loading.show();
            }
            
            $.ajax('https://www.googleapis.com/oauth2/v3/userinfo?access_token='+authResult.access_token).done(function(res) {
                user_id = res.email.replace(".","_");

            })

            
            startApp();
            window.setInterval(updateToken, 600000); //every 10 minutes (the token expires in 1 hour)

        } else {
            $loading.hide();
            $auth = $('#auth').show();
            $auth.find('#authorize-button').click(handleAuthClick);
        }
    });
}

function handleAuthClick(event) {
    gapi.auth.authorize({
        client_id: clientId,
        scope: scopes,
        immediate: false
    }, handleAuthResult);
    return false;
}

function updateToken() {
    //console.log('updateToken');
    gapi.auth.authorize({
        client_id: clientId,
        scope: scopes,
        immediate: true
    }, handleTokenUpdate);
}

function handleTokenUpdate(authResult) {
    if (authResult && !authResult.error) return;
    $loading.hide();
    $app.hide(); //remember to hide other top-level divs you might have
    alert("There's an error with your authentication.\nPlease refresh your browser.");
}

function getToken(secondTime) {
    var token = gapi.auth.getToken().access_token;
    if (!token && !secondTime) {
        updateToken();
        return getToken(1);
    }
    return token;
}