Implementation of renotify flag for Notifications.

Implement and plumb the renotify flag. This flag controls whether alert sound, lights,
and vibration are played again when a notification replaces a previous notification.

Changes for this issue are covered by Intent to Implement and Ship: Notification Renotify.

https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/k5n129-lM1A

BUG=442133

Review URL: https://codereview.chromium.org/1656243002

Cr-Commit-Position: refs/heads/master@{#374709}
34 files changed