This operates on a dictionary managed by another PersistentPrefStore.
It works by prefixing all the queries with the provided prefix.
This should allow having multiple pref stores work on the same
underlying file.
Bug: 336776819
Change-Id: I3445b562eb0eba28b7cbf8fbdb362ea5d33b67dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5512607
Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Ankush Singh <ankushkush@google.com>
Cr-Commit-Position: refs/heads/main@{#1301248}
35121a04e8