[Android Site Settings] Warn if notifications disabled

This CL has two effects when notifications are disabled for Chrome:

  1. Adds a link to 'Turn on permissions for Chrome' to the
  site settings of websites that have allowed/blocked notifications.

  2. Replaces Settings > Site Settings > Notifications page with a
  link to 'Turn on permission for Chrome in Android Settings'.

See screenshots at https://goo.gl/hVqEwN

These effects are guarded behind a flag in about://flags ('Enable
app notification status messaging').

Bug: 691898
Change-Id: Ib7b59905cfc4edcc2a80cd6aad45700714502abc
Reviewed-on: https://chromium-review.googlesource.com/1140633
Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Anita Woodruff <awdf@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576038}
4 files changed