[Notifications] Add a permission bubble client for desktop notifications.

BUG=332115

Review URL: https://codereview.chromium.org/153343002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249522 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249522