Add gerrit config lines to cq.cfg

Needed for the CQ to see Gerrit. Eg:
https://cs.chromium.org/chromium/tools/depot_tools/infra/config/cq.cfg?q=cq.cfg&sq=package:chromium&dr=C&l=9

BUG=skia:5627
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2251643005

Review-Url: https://codereview.chromium.org/2251643005
diff --git a/infra/branch-config/cq.cfg b/infra/branch-config/cq.cfg
index 78b0dc7..ccb72ae 100644
--- a/infra/branch-config/cq.cfg
+++ b/infra/branch-config/cq.cfg
@@ -4,6 +4,9 @@
 version: 1
 cq_name: "skia"
 cq_status_url: "https://chromium-cq-status.appspot.com"
+git_repo_url: "https://skia.googlesource.com/skia/"
+gerrit {}
+
 commit_burst_delay: 300
 max_commit_burst: 2