Does Google use app data to optimize its search engine?
Since PageRank counts the number of links to a page to determine how important it is, I would think that their todo or note app contains a lot of user-generated content (pages) too, that probably link to websites.
Given the amount of data they possess, if I were in your shoes, I'd assume that yes. Every single service, app, etc owned by them is more than likely to be used to create the most accurate profile about you.