Code review comment for lp:~gary-wzl77/unity-scopes-shell/fix_1576311

Looks good but I still need to test it in the silo. I'm confused by the need of emitting searchQueryChanged() signal though; did you find any issue if this signal is not emitted here? I checked unity8 code and they reset search themseleves before calling resetPrimaryNavigationTag(), so I'm not sure if this signal is really needed?