Expose the chromium waterfall in sheriff-o-matic.

-Store every waterfall's failures in ct-failure-analyzer
-Pick the list of failures based off the tree and link to the
right flakiness dashboard groups based off the tree.

NOTRY=true
R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/418253002

git-svn-id: svn://svn.chromium.org/blink/trunk@179197 bbb929c8-8fbe-4397-9dbb-9b2b20218538