Revert "Move kApplicationLocale pref to ui/base"

This reverts commit 6ad1cbd1bd26744de3a8d9be9e6fb824ac5c12b3.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Move kApplicationLocale pref to ui/base
> 
> We need to use the pref in components, so move the pref to ui/base so it
> can be accessed.
> 
> TBR=jam@chromium.org
> 
> Bug: 729596
> Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
> Change-Id: Iffc7c5c2f459340c14a74787defeab00c6c5589c
> Reviewed-on: https://chromium-review.googlesource.com/1125143
> Commit-Queue: Ran Ji <ranj@chromium.org>
> Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#573536}

TBR=sky@chromium.org,jam@chromium.org,asvitkine@chromium.org,ranj@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 729596
Change-Id: I950b8aa43701741de843172f24dd4a1b9887a5de
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Reviewed-on: https://chromium-review.googlesource.com/1133618
Reviewed-by: Ran Ji <ranj@chromium.org>
Commit-Queue: Ran Ji <ranj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574293}
32 files changed