CQ config: add gerrit CQAbility verifier.

Goal is to ensure that unreviewed and untrusted code isn't sent through
CQ to try bots, by accident or through malicious intent.

R=rmistry@google.com
BUG=chromium:692613
NOTRY=True

Change-Id: I750be91895f5b77229b8f4a22216f00eaa75f7a0
Reviewed-on: https://skia-review.googlesource.com/8620
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
diff --git a/infra/branch-config/cq.cfg b/infra/branch-config/cq.cfg
index a605f12..8a2ffe9 100644
--- a/infra/branch-config/cq.cfg
+++ b/infra/branch-config/cq.cfg
@@ -22,6 +22,10 @@
     no_lgtm_msg: "No LGTM from a valid reviewer yet. Please ask for an LGTM "
                  "from a\nfull Skia committer"
   }
+  gerrit_cq_ability {
+    committer_list: "project-skia-committers"
+    dry_run_access_list: "project-skia-tryjob-access"
+  }
 
   tree_status {
     tree_status_url: "https://skia-tree-status.appspot.com"