message: Use a python2 compatible exception class
  Summary: JSONDecodeError is a subclass of ValueError
  Test Plan: lstm_size_test passes
  Reviewers: georgep, jakeh
diff: @@ -735,7 +735,7 @@ def get_memory_size_from_events(events):
  return sum(js["memory"]["byTile"]["total"])
  except UnicodeDecodeError:
  pass
  - except json.decoder.JSONDecodeError:
  + except ValueError:
  pass
  return None
  