Update page_cycler to use sessionStorage.

Patch from Ahmad Sharif <asharif@chromium.org>.

This was landed previously as r56932 and reverted in
r57445.  Previous landing showed some flakiness/failures
in the DOM automation framework.  Relanding to verify
if this is fixed or still broken.

BUG=53491
TEST=page cyclers stay green

Review URL: http://codereview.chromium.org/5955002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69492 0039d316-1c4b-4281-b951-d872f2087c98