Replace base::StringPiece in //dbus with std::string_view

Bug: 691162
Change-Id: I37d4fed4cf78ada804b58525253b3f6f0300d9ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5040200
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Hyowon Kim <hyowon@igalia.com>
Cr-Commit-Position: refs/heads/main@{#1228616}
NOKEYCHECK=True
GitOrigin-RevId: eb6a4c4c4e90ae1c9589f9216520ca40ec0c946e
5 files changed