I believe this is coming from Activity Stream - if I disable Activity Stream and run Verify Integrity then the message goes away. Looking at http://searchfox.org/mozilla-central/rev/b258e6864ee3e809d40982bc5d0d5aff66a20780/browser/extensions/activity-stream/lib/PlacesFeed.jsm#148 the other functions for the observer aren't defined - we do define them in other places, e.g. http://searchfox.org/mozilla-central/rev/b258e6864ee3e809d40982bc5d0d5aff66a20780/services/sync/modules/engines/history.js#344
Component: Places → Activity Streams: Newtab
Product: Toolkit → Firefox
Fixed by https://github.com/mozilla/activity-stream/pull/3318 to be uplifted via bug 1395642.
Status: NEW → RESOLVED
Last Resolved: a year ago
Resolution: --- → FIXED
status-firefox57: --- → fixed
Target Milestone: --- → Firefox 57
Status: RESOLVED → VERIFIED
status-firefox57: fixed → verified
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