message: Rename private push/pop API and use from `stop_recording` method.
diff: @@ -723,21 +723,21 @@ class GradientTape(object):
  def __enter__(self):
  """Enters a context inside which operations are recorded on this tape."""
  - self._start_recording()
  + self._push_tape()
  return self
  def __exit__(self, typ, value, traceback):
  """Exits the recording context, no further operations are traced."""
  if self._recording:
  - self._stop_recording()
  + self._pop_tape()
  - def _start_recording(self):
  + def _push_tape(self):
  if self._recording:
  raise ValueError("Tape is already recording.")
  self._tape = tape.push_new_tape(persistent=self._persistent)
  self._recording = True
  - def _stop_recording(self):
  + def _pop_tape(self):
  if not self._recording:
  raise ValueError("Tape is not recording.")
  tape.pop_tape(self._tape)
  @@ -778,11 +778,11 @@ class GradientTape(object):
  if self._tape is None:
  raise RuntimeError(
  "Trying to stop recording a tape which is not recording.")
  - tape.pop_tape(self._tape)
  + self._pop_tape()
  try:
  yield
  finally:
  - tape.push_tape(self._tape)
  + self._push_tape()
  def reset(self):
  """Clears all information stored in this tape.
  @@ -815,8 +815,8 @@ class GradientTape(object):
  t.reset()
  ```
  """
  - self.__exit__(None, None, None)
  - self.__enter__()
  + self._pop_tape()
  + self._push_tape()
  def watched_variables(self):
  # Sorting variables by id, which is monotonically increasing in construction
  @@ -849,7 +849,7 @@ class GradientTape(object):
  "non-persistent tapes.")
  if self._recording:
  if not self._persistent:
  - self._stop_recording()
  + self._pop_tape()
  else:
  logging.log_first_n(logging.WARN,
  "Calling GradientTape.gradient on a persistent "
  