Google has released an update to Chrome for iOS which dramatically improves how it interacts with other Google apps which you may have installed on the same device.
First, if you've logged into Google from within Chrome, you'll be able to log into the other apps with a single click.
And anytime you're viewing a site within Chrome and tap a link, you'll have the option of opening that link in the appropriate app: YouTube, Maps, Google+ or Drive, instead of the Chrome browser. This is a preference that you can adjust in Chrome app settings, and Google states that support for additional apps is coming soon. Simply open Settings and tap on Google Apps. You'll see sliders for the currently available apps for which you can enable this feature.