Tool added to extract network traffic annotations.

tools/traffic_annotation/auditor/prepare_protobuf.py

+# Copyright (c) 2017 The Chromium 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 code is imported with modifications from
+'//infra/recipes-py/recipe_engine/env.py' to import protobuf from third_party
+directory instead of the one installed with current python libraries."""
+
+import contextlib
+import pkg_resources
+import os
+import sys
+
+
+def PrepareProtobuf():
+  CHROME_SRC = os.path.abspath(
+      os.path.join(os.path.dirname(os.path.realpath(__file__)),
+      "..", "..", ".."))
+  THIRD_PARTY = os.path.join(CHROME_SRC, 'third_party')
+  sys.path.insert(0, os.path.join(THIRD_PARTY, 'protobuf', 'python'))
+  sys.path.insert(
+      1, os.path.join(THIRD_PARTY, 'protobuf', 'third_party', 'six'))
+
+  @contextlib.contextmanager
+  def temp_sys_path():
+    orig_path = sys.path[:]
+    try:
+      yield
+    finally:
+      sys.path = orig_path
+
+  with temp_sys_path():
+    sys.path = [THIRD_PARTY]
+    sys.modules.pop('google', None)
+    pkg_resources.declare_namespace('google')
+    pkg_resources.fixup_namespace_packages(THIRD_PARTY)