Use ?cros GOMA_RPC_EXTRA_PARAMS for RBE_CHROMEOS.

BUG=b:162292728
TEST=./run_tests

Change-Id: I4f3bc62dbca5e940212d92117138efd394d8aa86
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2543563
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
Commit-Queue: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Tested-by: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Auto-Submit: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
diff --git a/api/controller/controller_util.py b/api/controller/controller_util.py
index e9e9dd0..df045bc 100644
--- a/api/controller/controller_util.py
+++ b/api/controller/controller_util.py
@@ -73,6 +73,8 @@
   if goma_message.goma_approach == common_pb2.GomaConfig.RBE_STAGING:
     goma_approach = goma_util.GomaApproach('?staging',
                                            'staging-goma.chromium.org', True)
+  elif goma_message.goma_approach == common_pb2.GomaConfig.RBE_CHROMEOS:
+    goma_approach = goma_util.GomaApproach('?cros', 'goma.chromium.org', True)
   else:
     goma_approach = goma_util.GomaApproach('?prod', 'goma.chromium.org', True)