public_key_manager: drop unused module

The last user of this module was removed earlier this year in
crrev.com/c/1659436 ("ctest: deprecate payload signing"), so
drop this entirely.

BUG=chromium:872441
TEST=CQ passes

Change-Id: I0342458d421788182574bbf1cfe0dc0cc8433631
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/1808024
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/lib/public_key_manager.py b/lib/public_key_manager.py
deleted file mode 100644
index 5d77682..0000000
--- a/lib/public_key_manager.py
+++ /dev/null
@@ -1,82 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-"""This module manages interactions between an image and a public key."""
-
-from __future__ import print_function
-
-import os
-import tempfile
-
-import constants
-from chromite.lib import cros_build_lib
-from chromite.lib import cros_logging as logging
-from chromite.lib import osutils
-from chromite.lib import path_util
-from crostestutils.lib import mount_helper
-
-
-class PublicKeyManager(object):
-  """Class wrapping interactions with a public key on an image."""
-  TARGET_KEY_PATH = 'usr/share/update_engine/update-payload-key.pub.pem'
-
-  def __init__(self, image_path, key_path):
-    """Initializes a manager with image_path and key_path we plan to insert."""
-    self.image_path = image_path
-    self.key_path = key_path
-    self._rootfs_dir = tempfile.mkdtemp(suffix='rootfs', prefix='tmp')
-    self._stateful_dir = tempfile.mkdtemp(suffix='stateful', prefix='tmp')
-
-    # Gather some extra information about the image.
-    try:
-      mount_helper.MountImage(image_path, self._rootfs_dir, self._stateful_dir,
-                              read_only=True)
-      self._full_target_key_path = os.path.join(
-          self._rootfs_dir, PublicKeyManager.TARGET_KEY_PATH)
-      self._is_key_new = True
-      if os.path.exists(self._full_target_key_path):
-        cmd = ['diff', self.key_path, self._full_target_key_path]
-        res = cros_build_lib.RunCommand(
-            cmd, print_cmd=False, error_code_ok=True, capture_output=True)
-        if not res.output:
-          self._is_key_new = False
-
-    finally:
-      mount_helper.UnmountImage(self._rootfs_dir, self._stateful_dir)
-
-  def __del__(self):
-    """Remove our temporary directories we created in init."""
-    os.rmdir(self._rootfs_dir)
-    os.rmdir(self._stateful_dir)
-
-  def AddKeyToImage(self):
-    """Adds the key specified in init to the image."""
-    if not self._is_key_new:
-      logging.info('Public key already on image %s.  No work to do.',
-                   self.image_path)
-      return
-
-    logging.info('Copying %s into %s', self.key_path, self.image_path)
-    try:
-      mount_helper.MountImage(self.image_path, self._rootfs_dir,
-                              self._stateful_dir, read_only=False)
-      dir_path = os.path.dirname(self._full_target_key_path)
-      osutils.SafeMakedirs(dir_path, sudo=True)
-      cmd = ['cp', '--force', '-p', self.key_path, self._full_target_key_path]
-      cros_build_lib.SudoRunCommand(cmd)
-    finally:
-      mount_helper.UnmountImage(self._rootfs_dir, self._stateful_dir)
-      self._MakeImageBootable()
-
-  def _MakeImageBootable(self):
-    """Makes the image bootable.  Note, it is only useful for non-vm images."""
-    from_dir, image = os.path.split(self.image_path)
-    if 'qemu' not in image:
-      from_dir = path_util.ToChrootPath(from_dir)
-      cmd = ['bin/cros_make_image_bootable', from_dir, image,
-             '--force_developer_mode']
-      cros_build_lib.RunCommand(
-          cmd, print_cmd=False, enter_chroot=True, cwd=constants.SOURCE_ROOT,
-          capture_output=True)