Switch Android GPU bot to use cloud storage for pixel reference images.

BUG=331125
R=navabi@chromium.org, navabi@google.com, skyostil@chromium.org

Review URL: https://codereview.chromium.org/97983005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243372 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243372