Declare/compute goma_enable_ats the same as other computed values.

Change-Id: Id3345773ded119aac8950b7a367ac176b3ef86df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2021185Reviewed-by: Simon Que <sque@chromium.org>
Commit-Queue: Simon Que <sque@chromium.org>
Auto-Submit: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736185}

infra/config/generated/cr-buildbucket.cfg

@@ -9454,7 +9454,7 @@ buckets: <
         name: "chromium"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "$build/goma:{\"enable_ats\":false,\"rpc_extra_params\":\"?tot\",\"server_host\":\"staging-goma.chromium.org\"}"
+        properties_j: "$build/goma:{\"rpc_extra_params\":\"?tot\",\"server_host\":\"staging-goma.chromium.org\"}"
         properties_j: "$kitchen:{\"devshell\":true,\"git_auth\":true}"
         properties_j: "mastername:\"chromium.goma\""
       >
@@ -9664,7 +9664,7 @@ buckets: <
         name: "chromium"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "$build/goma:{\"enable_ats\":false,\"rpc_extra_params\":\"?tot\",\"server_host\":\"staging-goma.chromium.org\"}"
+        properties_j: "$build/goma:{\"rpc_extra_params\":\"?tot\",\"server_host\":\"staging-goma.chromium.org\"}"
         properties_j: "$kitchen:{\"devshell\":true,\"git_auth\":true}"
         properties_j: "mastername:\"chromium.goma\""
       >

infra/config/lib/builders.star

@@ -157,13 +157,13 @@ def _goma_property(*, goma_backend, goma_debug, goma_enable_ats, goma_jobs, os):
 
   goma_enable_ats = _default('goma_enable_ats', goma_enable_ats)
   # TODO(crbug.com/1040754): Remove this flag.
-  if (goma_backend in (goma.backend.RBE_TOT, goma.backend.RBE_STAGING,
-                       goma.backend.RBE_PROD) and
-      os and os.category in (os_category.LINUX, os_category.WINDOWS)):
-    if goma_enable_ats != None:
-      goma_properties['enable_ats'] = goma_enable_ats
-    else:
-      goma_properties['enable_ats'] = True
+  if goma_enable_ats == _COMPUTE:
+    goma_enable_ats = (
+        os and os.category in (os_category.LINUX, os_category.WINDOWS) and
+        goma_backend in (goma.backend.RBE_TOT, goma.backend.RBE_STAGING,
+                         goma.backend.RBE_PROD))
+  if goma_enable_ats:
+    goma_properties['enable_ats'] = True
 
   goma_jobs = _default('goma_jobs', goma_jobs)
   if goma_jobs != None:
@@ -201,7 +201,7 @@ defaults = struct(
     cpu = lucicfg.var(),
     goma_backend = lucicfg.var(),
     goma_debug = lucicfg.var(default = False),
-    goma_enable_ats = lucicfg.var(),
+    goma_enable_ats = lucicfg.var(default = _COMPUTE),
     goma_jobs = lucicfg.var(),
     mastername = lucicfg.var(),
     os = lucicfg.var(),