Initialize per-ChromeOS-user NSS slots and provide the functions to access them.

BUG=302124
R=mmenke@chromium.org, rsleevi@chromium.org, xiyuan@chromium.org

Review URL: https://codereview.chromium.org/53763003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239266 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239266
Introduces the image assets for app-list speech UI.

TBR=xiyuan@chromium.org, oshima@chromium.org
BUG=313904
TEST=none

Review URL: https://codereview.chromium.org/106323003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239267 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239267