Google new iOS search app now lets you search privately using incognito mode but the cool part is that you can leave the app and return to your private search.
The way they control the privacy in that instance is using Touch ID. So you use your finger print to unlock your private search, as you left off with it in the iOS app.
Google wrote:
Your searches are your business. That’s why we’ve added the ability to search privately with incognito mode in the Google app for iOS. When you have incognito mode turned on in your settings, your search and browsing history will not be saved. And for added security, you can enable Touch ID for incognito mode, ensuring that only you can re-enter your existing incognito session if you exit the app.
Here is how to set it up:
Forum discussion at Google+.