Use qualified base::make_optional in optional_unittest.cc

Unqualified usage of make_optional causes a compile error if:
 - It's compiler in C++17 mode and <optional> is included.
 - The parameter of make_optional is in std namespace, such as
   std::string.
As std::make_optional is pulled by ADL rule and conflicts to
base::make_optional in this situation.

This CL replaces them with qualified base::make_optional, and
replaces others for consistency.

Change-Id: If91190dc64306be147ba248d4f523892cda7c958
Reviewed-on: https://chromium-review.googlesource.com/c/1282512
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600361}
(cherry picked from commit d2e73f1115bfed906f2a10dc69aebced6774bac3)
2 files changed