Repro:
Run Chrome with --enable-features=NTPTilesInInstantService
Click the profile button in the top right -> "Manage people"
Hit NOTREACHED in favicon_service_factory.cc(45): Check failed: false. This profile is OffTheRecord

Looks like for whatever reason, the profile switcher creates an incognito profile, and its InstantService creates a MostVisitedSites instance, which in turns causes the NOTREACHED in FaviconServiceFactory.


Possible solutions:

- In InstantService, don't create MostVisitedSites if we're off the record. (A bit weird IMO - clients shouldn't have to care about that. If we go this way, we should at least put a comment on the MVFactory and/or rename the method.)

- In ChromeMostVisitedSitesFactory, if we're off the record, don't create a MostVisitedSites instance at all, similar to what TopSites does. (Preferred solution IMO.)

- In ChromeMostVisitedSitesFactory, if we're off the record, pass a null FaviconService to the MostVisitedSites (this seems weird and inconsistent).