Limit the layout_test batch size for *SAN builds.

Tools/Scripts/webkitpy/layout_tests/port/base.py

Index: Tools/Scripts/webkitpy/layout_tests/port/base.py
diff --git a/Tools/Scripts/webkitpy/layout_tests/port/base.py b/Tools/Scripts/webkitpy/layout_tests/port/base.py
index ea4b366894efeba6e802717d820e2397a67b879d..6131e57a68b63d8296b65e0d9191b89795aa7fba 100644
--- a/Tools/Scripts/webkitpy/layout_tests/port/base.py
+++ b/Tools/Scripts/webkitpy/layout_tests/port/base.py
@@ -258,6 +258,16 @@ class Port(object):
             self._pretty_patch_available = self.check_pretty_patch(logging=False)
         return self._pretty_patch_available
 
+    def default_batch_size(self):
+        """Return the default batch size to use for this port."""
+        if self.get_option('enable_sanitizer'):
+            # ASAN/MSAN/TSAN use more memory than regular content_shell. Their
+            # memory usage may also grow over time, up to a certain point.
+            # Relaunching the driver periodically helps keep it under control.
+            return 50
+        # The default is infinte batch size.
+        return None
+
     def default_child_processes(self):
         """Return the number of drivers to use for this port."""
         if self.get_option('enable_sanitizer'):