Relax same-origin policy for ServiceWorker openWindow() in Chromium.

Per blink-dev discussion:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/vCd9TysLAso/UcNQMme-9LsJ

This is relaxing the browser-side checks in order to no longer kill a
renderer process if it tries to open a cross-origin window from a service
worker. It will allow the Blink restriction to be relaxed:
https://codereview.chromium.org/985043002

The browser process now checks whether the renderer process is allowed
access to the given URL, blocking access to special URLs like chrome://.

BUG=457187

Review URL: https://codereview.chromium.org/980383004

Cr-Commit-Position: refs/heads/master@{#319648}
5 files changed