[FeatureList] Change GetApplicationLocale() in VariationsServiceClient to be a local function. [2/3]

Before this function uses a pref in Chrome so we need to override it in Chrome
to access that pref value.

As a followup for this cl https://crrev.com/c/1135198,
now we can access the pref directly in componment/ and we no longer need to do that.

This CL comes from https://crrev.com/c/1140356. See previous discussion there.

Bug:729596
TBR=asvitkine@chromium.org

Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I7bf5631b81436344ccb17aaa2a8d6ac4167f5d7f
Reviewed-on: https://chromium-review.googlesource.com/1147481
Commit-Queue: Xi Han <hanxi@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586711}
17 files changed