This adds just the files. The code to use these files will be added
separately in a change list that can be delivered through the commit
queue (change lists with binary files like the ones in this chane cannot
use the commit queue).

This also adds some notification_expand*.png files which are renamed
versions of existing notifications_expand*.png files. This is the first
step in renaming those files. The second step, to be delivered in a
follow-up change list, will switch the code to use the new names. A
third step, coming in a third change list, will remove the versions of
the file with the old name.

BUG=232963

Review URL: https://codereview.chromium.org/14362011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195341 0039d316-1c4b-4281-b951-d872f2087c98