[WebSocket] Don't use timers to post tasks

Replace the use of zero-length timers in blink::DOMWebSocket with direct
use of the PostTask API. This slightly improves clarity and efficiency.

BUG=856651

Change-Id: Ib6003fb9861a59513477eafcaa07e02eacef1271
Reviewed-on: https://chromium-review.googlesource.com/1151045
Commit-Queue: Adam Rice <ricea@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580053}
2 files changed