Modify Skia recipes to allow running XSAN on Swarming.

scripts/slave/recipe_modules/skia/default_flavor.py

Index: scripts/slave/recipe_modules/skia/default_flavor.py
diff --git a/scripts/slave/recipe_modules/skia/default_flavor.py b/scripts/slave/recipe_modules/skia/default_flavor.py
index 537ef34bb6e6fdd34318d022c29c5ca3a9b4787d..0881d21c42276d9555c8af990992bc6734c3cc72 100644
--- a/scripts/slave/recipe_modules/skia/default_flavor.py
+++ b/scripts/slave/recipe_modules/skia/default_flavor.py
@@ -210,6 +210,13 @@ class DefaultFlavorUtils(object):
     if 'CommandBuffer' in self._skia_api.builder_name:
       self._skia_api._run_once(self.build_command_buffer)
 
+  def copy_extra_build_products(self, swarming_out_dir):
+    """Copy extra build products to specified directory.
+
+    Copy flavor-specific build products to swarming_out_dir for use in test and
+    perf steps. Only called if running_in_swarming."""
+    pass
+
   @property
   def out_dir(self):
     """Flavor-specific out directory."""