[autotest] Move _should_batch_with closer to use site

BUG=chromium:672348
TEST=None

Change-Id: I3e7a5f9cd4921be9bda6fd7fb5b167f9c2e06040
Reviewed-on: https://chromium-review.googlesource.com/453268
Commit-Ready: Allen Li <ayatane@chromium.org>
Tested-by: Allen Li <ayatane@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
diff --git a/server/cros/dynamic_suite/suite.py b/server/cros/dynamic_suite/suite.py
index 4964bfc..59aa641 100644
--- a/server/cros/dynamic_suite/suite.py
+++ b/server/cros/dynamic_suite/suite.py
@@ -467,6 +467,18 @@
         return _ControlFileRetriever(cf_getter)
 
 
+def _should_batch_with(cf_getter):
+    """Return whether control files should be fetched in batch.
+
+    This depends on the control file getter and configuration options.
+
+    @param cf_getter: a control_file_getter.ControlFileGetter used to list
+           and fetch the content of control files
+    """
+    return (ENABLE_CONTROLS_IN_BATCH
+            and isinstance(cf_getter, control_file_getter.DevServerGetter))
+
+
 class _ControlFileRetriever(object):
     """Retrieves control files.
 
@@ -635,18 +647,6 @@
     return tests
 
 
-def _should_batch_with(cf_getter):
-    """Return whether control files should be fetched in batch.
-
-    This depends on the control file getter and configuration options.
-
-    @param cf_getter: a control_file_getter.ControlFileGetter used to list
-           and fetch the content of control files
-    """
-    return (ENABLE_CONTROLS_IN_BATCH
-            and isinstance(cf_getter, control_file_getter.DevServerGetter))
-
-
 def get_test_source_build(builds, **dargs):
     """Get the build of test code.