This fixes an `Unhandled chrome.send("getApps");` error when creating a new tab.
Creating a new tab initially loads chrome://newtab which should then be
rewritten to chrome://new-tab-page for normal profiles in
HandleNewTabURLRewrite. Failure to rewrite the URL results in the loading of
NewTabUI instead of the expected NewTabPageUI. NewTabUI loads different
resources for normal vs incognito/guest profiles (new_tab.js vs
incognito_tab.js), and new_tab.js calls chrome.send("getApps") via
page_list_view.js. This then fails in WebUIImpl::ProcessWebUIMessage because
the message is unhandled.
a6a8c0e845