As demonstrated by the MergeProfileWithDifferentGuid[1] test, merging two identical profile results in keeping the usage stats of the sync profile. Instead, the more recent use date should be kept and the use counts should be added.


[1]: https://code.google.com/p/chromium/codesearch#chromium/src/components/browser_sync/browser/profile_sync_service_autofill_unittest.cc&l=1207