GitLab

- Replaces ScopedTestNSSDB by ScopedTestNSSChromeOSUser, which is the choice for ChromeOS.
- Removes the deprecated net::NSSCertDatabase::GetInstance() call.
- Changes the build target from brower_test to unit_test, as originally intended.

BUG=329735, 210525

Review URL: https://codereview.chromium.org/407443008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284112 0039d316-1c4b-4281-b951-d872f2087c98