message: Capture a reference to TF_DeleteGraph in ScopedTFGraph.
  This enables us to free the underlying TF_Graph object at process shutdown, and therefore satifies leak checkers.
diff: @@ -44,12 +44,14 @@ class ScopedTFGraph(object):
  def __init__(self):
  self.graph = c_api.TF_NewGraph()
  + # Note: when we're destructing the global context (i.e when the process is
  + # terminating) we may have already deleted other modules. By capturing the
  + # DeleteGraph function here, we retain the ability to cleanly destroy the
  + # graph at shutdown, which satisfies leak checkers.
  + self.deleter = c_api.TF_DeleteGraph
  def __del__(self):
  - # Note: when we're destructing the global context (i.e when the process is
  - # terminating) we can have already deleted other modules.
  - if c_api is not None and c_api.TF_DeleteGraph is not None:
  - c_api.TF_DeleteGraph(self.graph)
  + self.deleter(self.graph)
  class ScopedTFImportGraphDefOptions(object):
  