GitLab

Adds fuzzer for policies, currently fuzzes only ChromeDeviceSettingsProto.

ASan' out/libfuzzer && ninja -C out/libfuzzer policy_fuzzer &&
out/libfuzzer/policy_fuzzer

Test: tools/mb/mb.py gen -m chromium.fuzz -b 'Libfuzzer Upload Chrome OS
Bug: 811690
Change-Id: Ic4c0a923006515f75bcb51c38f00be5701ab81a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1845000
Commit-Queue: Olya Kalitova <okalitova@chromium.org>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705929}