Enables GN build on windows

tools/find_depot_tools.py

+# Copyright (c) 2011 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.
+"""Small utility function to find depot_tools and add it to the python path.
+Will throw an ImportError exception if depot_tools can't be found since it
+imports breakpad.
+"""
+
+import os
+import sys
+
+
+def IsRealDepotTools(path):
+  return os.path.isfile(os.path.join(path, 'gclient.py'))
+
+
+def add_depot_tools_to_path():
+  """Search for depot_tools and add it to sys.path."""
+  # First look if depot_tools is already in PYTHONPATH.
+  for i in sys.path:
+    if i.rstrip(os.sep).endswith('depot_tools') and IsRealDepotTools(i):
+      return i
+  # Then look if depot_tools is in PATH, common case.
+  for i in os.environ['PATH'].split(os.pathsep):
+    if IsRealDepotTools(i):
+      sys.path.append(i.rstrip(os.sep))
+      return i
+  # Rare case, it's not even in PATH, look upward up to root.
+  root_dir = os.path.dirname(os.path.abspath(__file__))
+  previous_dir = os.path.abspath(__file__)
+  while root_dir and root_dir != previous_dir:
+    i = os.path.join(root_dir, 'depot_tools')
+    if IsRealDepotTools(i):
+      sys.path.append(i)
+      return i
+    previous_dir = root_dir
+    root_dir = os.path.dirname(root_dir)
+  print >> sys.stderr, 'Failed to find depot_tools'
+  return None
+
+add_depot_tools_to_path()
+
+# pylint: disable=W0611
+import breakpad