[fharper1961]

Seems to me like the main value for Google is the data from all the apps that have Fabric SDK integration (e.g. Crashlytics).

Quote from the Fabric blog post https://fabric.io/blog/fabric-joins-google

"Fabric has grown to reach 2.5 billion active mobile devices".

[guelo]

They have the app data on the Android side which is probably a decent proxy for the iOS app market, but Crashlytics gives them direct visibility into a sizable chunk of the ios market.