The country code from the variations seed was only written to prefs on
the first seed fetch of a session. Subsequent 304 Not Modified responses
carrying a new X-Country header were silently ignored, so country-keyed
components such as the NTT and ads resource components would not update
when the user's location changed mid-session via VPN. The fix writes the
country code on every 304 response that carries a non-empty X-Country
header. This does not affect Chromium field trial membership, which is
evaluated once at startup from the stored seed.
Terry Mancey
25059f6aaf