Service Workers: Move chromium-specific test to chromium/ subdir

BUG=393721
TBR=dominicc@chromium.org

Review URL: https://codereview.chromium.org/431973005

git-svn-id: svn://svn.chromium.org/blink/trunk@179414 bbb929c8-8fbe-4397-9dbb-9b2b20218538