Add path for NaCl pepper2 based plugin.

BUG= http://code.google.com/p/nativeclient/issues/detail?id=933
TEST=none

Original patch by Noel Allen.

Review URL: http://codereview.chromium.org/5740007/


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69285 0039d316-1c4b-4281-b951-d872f2087c98