Trivial ppapi/c headers changes

Trivial changes to C headers for consistency with generated code
prior to throwing the switch.

TEST= tryserver
BUG= http://code.google.com/p/chromium/issues/detail?id=76271
Review URL: http://codereview.chromium.org/7360008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@92550 0039d316-1c4b-4281-b951-d872f2087c98