Revert "depot_tools: Stop using oauth2client"

This reverts commit 55e5853e.

Reason for revert:

  File "PRESUBMIT.py", line 11, in CheckChangeOnCommit
    return input_api.canned_checks.CheckChangedLUCIConfigs(input_api, output_api)
  File "/usr/local/google/home/abennetts/cr/depot_tools/presubmit_canned_checks.py", line 1421, in CheckChangedLUCIConfigs
    acc_tkn = authenticator.get_access_token()
  File "/usr/local/google/home/abennetts/cr/depot_tools/auth.py", line 414, in get_access_token
    if not self._external_token and allow_user_interaction:
AttributeError: 'Authenticator' object has no attribute '_external_token'


Original change's description:
> depot_tools: Stop using oauth2client
> 
> Bug: 1001756
> Change-Id: I8a0ca2b0f44b20564a9d3192543a7a69788d8d87
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1854898
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
> Reviewed-by: Vadim Shtayura <vadimsh@chromium.org>

TBR=vadimsh@chromium.org,ehmaldonado@chromium.org

Change-Id: I94cf38e82e53e51c66efcb99c51f0e1418e86f49
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1001756, 1015285
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1866184Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

tests/auth_test.py

@@ -5,7 +5,7 @@
 
 """Unit Tests for auth.py"""
 
-import contextlib
+import __builtin__
 import datetime
 import json
 import logging
@@ -16,35 +16,37 @@ import time
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
-from third_party import mock
+
+from testing_support import auto_stub
 from third_party import httplib2
+from third_party import mock
 
 import auth
 
 
-def _mockLocalAuth(account_id, secret, rpc_port):
-  mock_luci_context = {
+class TestLuciContext(auto_stub.TestCase):
+  def setUp(self):
+    auth._get_luci_context_local_auth_params.clear_cache()
+
+  def _mock_local_auth(self, account_id, secret, rpc_port):
+    self.mock(os, 'environ', {'LUCI_CONTEXT': 'default/test/path'})
+    self.mock(auth, '_load_luci_context', mock.Mock())
+    auth._load_luci_context.return_value = {
       'local_auth': {
-          'default_account_id': account_id,
-          'secret': secret,
-          'rpc_port': rpc_port,
+        'default_account_id': account_id,
+        'secret': secret,
+        'rpc_port': rpc_port,
       }
-  }
-  mock.patch('auth._load_luci_context', return_value=mock_luci_context).start()
-  mock.patch('os.environ', {'LUCI_CONTEXT': 'default/test/path'}).start()
-
-
-def _mockResponse(status, content):
-  mock_response = (mock.Mock(status=status), content)
-  mock.patch('auth.httplib2.Http.request', return_value=mock_response).start()
-
+    }
 
-class TestLuciContext(unittest.TestCase):
-  def setUp(self):
-    auth._get_luci_context_local_auth_params.clear_cache()
+  def _mock_loc_server_resp(self, status, content):
+    mock_resp = mock.Mock()
+    mock_resp.status = status
+    self.mock(httplib2.Http, 'request', mock.Mock())
+    httplib2.Http.request.return_value = (mock_resp, content)
 
   def test_all_good(self):
-    _mockLocalAuth('account', 'secret', 8080)
+    self._mock_local_auth('account', 'secret', 8080)
     self.assertTrue(auth.has_luci_context_local_auth())
 
     expiry_time = datetime.datetime.min + datetime.timedelta(hours=1)
@@ -55,18 +57,18 @@ class TestLuciContext(unittest.TestCase):
       'expiry': (expiry_time
                  - datetime.datetime.utcfromtimestamp(0)).total_seconds(),
     }
-    _mockResponse(200, json.dumps(resp_content))
+    self._mock_loc_server_resp(200, json.dumps(resp_content))
     params = auth._get_luci_context_local_auth_params()
     token = auth._get_luci_context_access_token(params, datetime.datetime.min)
     self.assertEqual(token.token, 'token')
 
   def test_no_account_id(self):
-    _mockLocalAuth(None, 'secret', 8080)
+    self._mock_local_auth(None, 'secret', 8080)
     self.assertFalse(auth.has_luci_context_local_auth())
     self.assertIsNone(auth.get_luci_context_access_token())
 
   def test_incorrect_port_format(self):
-    _mockLocalAuth('account', 'secret', 'port')
+    self._mock_local_auth('account', 'secret', 'port')
     self.assertFalse(auth.has_luci_context_local_auth())
     with self.assertRaises(auth.LuciContextAuthError):
       auth.get_luci_context_access_token()
@@ -79,7 +81,7 @@ class TestLuciContext(unittest.TestCase):
       'access_token': 'token',
       'expiry': 1,
     }
-    _mockResponse(200, json.dumps(resp_content))
+    self._mock_loc_server_resp(200, json.dumps(resp_content))
     with self.assertRaises(auth.LuciContextAuthError):
       auth._get_luci_context_access_token(
           params, datetime.datetime.utcfromtimestamp(1))
@@ -92,13 +94,13 @@ class TestLuciContext(unittest.TestCase):
       'access_token': 'token',
       'expiry': 'dead',
     }
-    _mockResponse(200, json.dumps(resp_content))
+    self._mock_loc_server_resp(200, json.dumps(resp_content))
     with self.assertRaises(auth.LuciContextAuthError):
       auth._get_luci_context_access_token(params, datetime.datetime.min)
 
   def test_incorrect_response_content_format(self):
     params = auth._LuciContextLocalAuthParams('account', 'secret', 8080)
-    _mockResponse(200, '5')
+    self._mock_loc_server_resp(200, '5')
     with self.assertRaises(auth.LuciContextAuthError):
       auth._get_luci_context_access_token(params, datetime.datetime.min)