Clear Plugins data in Default and Pref providers.

Bug: 1142861
Change-Id: Ia1f80f799a7b809316fb040d49d8cc3c99946453
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2503692


Auto-Submit: Illia Klimov <elklm@google.com>
Commit-Queue: Illia Klimov <elklm@google.com>
Reviewed-by: Christian Dullweber <dullweber@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824836}