The implicit constructor is deprecated since version 7.3, hence can be
removed in 7.4.

R=ulan@chromium.org

Change-Id: I54a530240648c1721924195d7fccc157d483e6d8
Reviewed-on: https://chromium-review.googlesource.com/c/1436018Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59116}