Whitelist two more apps for use in public sessions

This CL whitelists two more apps for use in public sessions, Google Keep
demo and Google+ Photos demo. Both will be used in retail mode.

The CL also updates the descriptions of existing whitelisted apps to
clarify which ones are demo versions of actual apps.

BUG=317909
TEST=None

Review URL: https://codereview.chromium.org/88293003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238410 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238410
Adding templating for chrome repos:
store, nacl, multidevice, devtools

patch from issue 100723002

Eli, I've added you as a reviewer. This includes very simple starter file for native client so that we can push content migration. I need a native client owner to approve this change.

TBR=eliben@chromium.org

Review URL: https://codereview.chromium.org/100783002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238411 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238411