Add presubmit warning about deprecated compiled_resources.gyp

PRESUBMIT_test_mocks.py

Index: PRESUBMIT_test_mocks.py
diff --git a/PRESUBMIT_test_mocks.py b/PRESUBMIT_test_mocks.py
index 8e15d8cf53d37ee1c60c5d8c05d0ea819598426e..f68c13441c413d8964258503cac471a01fc3b512 100644
--- a/PRESUBMIT_test_mocks.py
+++ b/PRESUBMIT_test_mocks.py
@@ -97,6 +97,9 @@ class MockFile(object):
     self._new_contents = new_contents
     self._changed_contents = [(i + 1, l) for i, l in enumerate(new_contents)]
 
+  def Action(self):
+    return 'A'  # TODO(dbeam): feel free to change if your test actually uses.
+
   def ChangedContents(self):
     return self._changed_contents