GitLab

Modernize content/public/test/browser_test_utils.cc.

- Use auto, = default, and std::make_unique().
- Remove content:: in namespace content.
- Fix a few nits along the way.

Change-Id: I55912384dcb5dff2d9a16b14706dca687b65aa75
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404955Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806302}