I just checked MDN, since I've had problems with html5rocks tutorials being outdated due to specs changing in the past (not related to localStorage though), but all pages I can find on it seem to overlook the whole quota aspect[0]. However, the Chrome dev page on the topic[1] mentions this:

> Unlimited storage is similar to persistent storage, but it is available only to Chrome apps and extensions (.crx files). The size of unlimited storage is limited only by the availability of space in the user's hard drive. You can ask for the unlimitedStorage permission in the manifest file for an app or extension. At installation, the user is informed of permissions required by the app or extension. By proceeding with the installation, the user implicitly grants permission for all pages whose URLs are listed in the manifest.json file.

[0] https://developer.mozilla.org/en-US/docs/Web/API/Storage

[1] https://developer.chrome.com/apps/offline_storage