Clean up a few more unused globals.

Found by clang's new -Wunused-const-variable.

BUG=290204
R=akalin@chromium.org, avi@chromium.org, isherman@chromium.org, jamesr@chromium.org, joi@chromium.org, sergeyu@chromium.org, sky@chromium.org, thestig@chromium.org, xhwang@chromium.org

Review URL: https://codereview.chromium.org/24649002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225273 0039d316-1c4b-4281-b951-d872f2087c98