Updated name in constructor of our override BravePrefProvider.

Chromim change:

https://chromium.googlesource.com/chromium/src/+/94c80d547af89125e18831420d57562117c8e348

commit 94c80d547af89125e18831420d57562117c8e348
Author: Ramin Halavati <rhalavati@chromium.org>
Date:   Tue Jun 4 06:13:36 2019 +0000

    Replace incognito with off_the_record in ContentSettingsPref*.

    ContentSettingsPref and ContentSettingsPrefProfovider classes receive
    an |incognito| argument that actually triggers the off-the-record
    behavior and is not necessarily an incognito mode specifier.
    The argument and all related items are renamed to off_the_record to
    remove ambiguity.

    Bug: 968028