Add NotifyOnPermissionLevelChanged implementation of notification
provider API

When an extension/app with notificationProvider permission shows a user
information about sources of the notifications, the notifiers. When the
user wants to allow or disallow one notifier, NotifyOnPermissionLevelChanged
can be used to inform the notifier that its permission level was changed.

BUG=397197

Review URL: https://codereview.chromium.org/468813002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290105 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed