tools/battor_agent: Adds battor_agent_unittests to waterfall

BUG=571458

Review URL: https://codereview.chromium.org/1645103002

Cr-Commit-Position: refs/heads/master@{#372214}
diff --git a/testing/buildbot/gn_isolate_map.pyl b/testing/buildbot/gn_isolate_map.pyl
index 52ec5a2..bbcd120 100644
--- a/testing/buildbot/gn_isolate_map.pyl
+++ b/testing/buildbot/gn_isolate_map.pyl
@@ -73,6 +73,10 @@
     "label": "//base:base_unittests",
     "type": "console_test_launcher",
   },
+  "battor_agent_unittests": {
+    "label": "//tools/battor_agent:battor_agent_unittests",
+    "type": "console_test_launcher",
+  },
   "blimp_unittests": {
     "label": "//blimp:blimp_unittests",
     "type": "console_test_launcher",