It's Chrome for Android only - https://support.google.com/chrome/answer/4410268?p=mobile_protected_content&rd=1 https://support.google.com/chrome/answer/4410268

It's Chrome for Android only - https://support.google.com/chrome/answer/4410268?p=mobile_protected_content&rd=1 https://support.google.com/chrome/answer/4410268?p=mobile_pr... I'm assuming it's a nonstandard thing they're experimenting with that provides a combination of device ID and browser ID (assuming Chrome on Android is similar to it on desktop, where each install is branded with a number).