Chrome OS: Create a preference to support fine grained time zone detection.

This CL adds new user preference ResolveTimezoneByGeolocationMethod (enum) that
superceeds the existing boolean preference ResolveTimezoneByGeolocation.

Device preference ResolveDeviceTimezoneByGeolocation is also replaced with
ResolveDeviceTimezoneByGeolocationMethod.

We migrate local ResolveTimezoneByGeolocation preference value to
ResolveTimezoneByGeolocationMethod and store migration flag locally.

This Cl should not introduce functional changes, as UI still allows to select
only previously supported resolving methods.

Bug: 721578
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I7dd73663b99f66d63ae83538dbcaa753fd6c634d
Reviewed-on: https://chromium-review.googlesource.com/746149
Reviewed-by: Michael Giuffrida <[email protected]>
Reviewed-by: Steven Bennetts <[email protected]>
Commit-Queue: Alexander Alekseev <[email protected]>
Cr-Commit-Position: refs/heads/master@{#515805}
13 files changed