Part of the new world order of renaming the Obj::Data classes to ObjState.

BUG=angleproject:1363

Change-Id: I15cf002b8b093d687f540b9e86f045874af24a7e
Reviewed-on: https://chromium-review.googlesource.com/340740Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>