Add missing include to chrome_authenticator_request_delegate.cc

ListPrefUpdate is used in this file. It fails to compile with some build
configurations.

Change-Id: Icebb5b6f0ab59d4fad05ce3c1d2b6b64225f77ea
Reviewed-on: https://chromium-review.googlesource.com/c/1286467
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Commit-Queue: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600367}
1 file changed