mac: Replace notification wrench pdf with a png

BUG=111101
TEST=If on 10.8, change NotificationUIManager::Create() to always create
non-native notifications. Go to http://dangercove.github.com/html5-notifications/
and create a plain text notification, the wrench image should show up fine in
normal, hover, and pressed states.

Before: http://imgur.com/yBAz0,XM7fI#0
After: http://imgur.com/yBAz0,XM7fI#1


Review URL: https://chromiumcodereview.appspot.com/11691003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174717 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed