Change random-daily-seed to random-seeded.

As per https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/pIq9k_2vmzM,
use a fixed seed instead of a daily changing seed.

Review URL: https://codereview.chromium.org/19250004

git-svn-id: svn://svn.chromium.org/blink/trunk@154245 bbb929c8-8fbe-4397-9dbb-9b2b20218538