This CL contains the new asserts for the media controls. I'll remove the old stuff
after the webkit side of the change is in.

BUG=88489
TEST=None needed. Purely asset additions.

Review URL: http://codereview.chromium.org/7278037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@91771 0039d316-1c4b-4281-b951-d872f2087c98