There are some OS_NACL ifdefs in pdf/{instance.cc/out_of_process_instance.cc}.
I assume these are from long ago when we tried to get PDF running in NaCl but
I believe that at present many more changes would be required to get it
running in NaCl again so we might as well remove these.
Review URL: https://codereview.chromium.org/424763008
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@286927 0039d316-1c4b-4281-b951-d872f2087c98