Rename isSystemLocationEnabled to isLocationEnabled, as per internal review (185995).
The function is still used by the non-public repo, so I'll do this in two steps (provide an alternate function and then remove the old one once all callers have been converted).
BUG=434920
TBR=bauerb
NOTRY=true
(TBR-ing after review because this style-guide violation spotted by the bot is temporary until the rename is complete and the end-result, which will follow shortly, is style-guide compliant so fixing this would be throw-away work).
Review URL: https://codereview.chromium.org/
755643006
Cr-Commit-Position: refs/heads/master@{#307895}