Update from https://crrev.com/315085

build/gyp_chromium

 #!/usr/bin/env python
 
 # Copyright (c) 2012 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 script is wrapper for Chromium that adds some support for how GYP
 # is invoked by Chromium beyond what can be done in the gclient hooks.
 
+import argparse
 import glob
 import gyp_environment
 import os
 import re
 import shlex
 import subprocess
 import string
 import sys
 import vs_toolchain
 
 script_dir = os.path.dirname(os.path.realpath(__file__))
 chrome_src = os.path.abspath(os.path.join(script_dir, os.pardir))
 
 sys.path.insert(0, os.path.join(chrome_src, 'tools', 'gyp', 'pylib'))
 import gyp
 
 # Assume this file is in a one-level-deep subdirectory of the source root.
 SRC_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 
 # Add paths so that pymod_do_main(...) can import files.
+sys.path.insert(1, os.path.join(chrome_src, 'android_webview', 'tools'))
 sys.path.insert(1, os.path.join(chrome_src, 'build', 'android', 'gyp'))
 sys.path.insert(1, os.path.join(chrome_src, 'tools'))
 sys.path.insert(1, os.path.join(chrome_src, 'tools', 'generate_shim_headers'))
 sys.path.insert(1, os.path.join(chrome_src, 'tools', 'grit'))
 sys.path.insert(1, os.path.join(chrome_src, 'chrome', 'tools', 'build'))
 sys.path.insert(1, os.path.join(chrome_src, 'chromecast', 'tools', 'build'))
 sys.path.insert(1, os.path.join(chrome_src, 'native_client', 'build'))
 sys.path.insert(1, os.path.join(chrome_src, 'native_client_sdk', 'src',
     'build_tools'))
 sys.path.insert(1, os.path.join(chrome_src, 'remoting', 'tools', 'build'))
@@ skipping 77 matching lines @@
         e.filename = os.path.abspath(supplement)
         raise
       variables = file_data.get('variables', [])
       for v in variables:
         supp_items += [(v, str(variables[v]))]
 
   # GYP defines from the environment.
   env_items = ProcessGypDefinesItems(
       shlex.split(os.environ.get('GYP_DEFINES', '')))
 
-  # GYP defines from the command line. We can't use optparse since we want
-  # to ignore all arguments other than "-D".
-  cmdline_input_items = []
-  for i in range(len(sys.argv))[1:]:
-    if sys.argv[i].startswith('-D'):
-      if sys.argv[i] == '-D' and i + 1 < len(sys.argv):
-        cmdline_input_items += [sys.argv[i + 1]]
-      elif len(sys.argv[i]) > 2:
-        cmdline_input_items += [sys.argv[i][2:]]
+  # GYP defines from the command line.
+  parser = argparse.ArgumentParser()
+  parser.add_argument('-D', dest='defines', action='append', default=[])
+  cmdline_input_items = parser.parse_known_args()[0].defines
   cmdline_items = ProcessGypDefinesItems(cmdline_input_items)
 
   vars_dict = dict(supp_items + env_items + cmdline_items)
   return vars_dict
 
 
 def GetOutputDirectory():
   """Returns the output directory that GYP will use."""
-  # GYP generator flags from the command line. We can't use optparse since we
-  # want to ignore all arguments other than "-G".
-  needle = '-Goutput_dir='
-  cmdline_input_items = []
-  for item in sys.argv[1:]:
+
+  # Handle command line generator flags.
+  parser = argparse.ArgumentParser()
+  parser.add_argument('-G', dest='genflags', default=[], action='append')
+  genflags = parser.parse_known_args()[0].genflags
+
+  # Handle generator flags from the environment.
+  genflags += shlex.split(os.environ.get('GYP_GENERATOR_FLAGS', ''))
+
+  needle = 'output_dir='
+  for item in genflags:
     if item.startswith(needle):
       return item[len(needle):]
 
-  env_items = shlex.split(os.environ.get('GYP_GENERATOR_FLAGS', ''))
-  needle = 'output_dir='
-  for item in env_items:
-    if item.startswith(needle):
-      return item[len(needle):]
-
-  return "out"
+  return 'out'
 
 
 def additional_include_files(supplemental_files, args=[]):
   """
   Returns a list of additional (.gypi) files to include, without duplicating
   ones that are already specified on the command line. The list of supplemental
   include files is passed in as an argument.
   """
   # Determine the include files specified on the command line.
   # This doesn't cover all the different option formats you can use,
@@ skipping 157 matching lines @@
 
   if not use_analyzer:
     vs2013_runtime_dll_dirs = vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
     if vs2013_runtime_dll_dirs:
       x64_runtime, x86_runtime = vs2013_runtime_dll_dirs
       vs_toolchain.CopyVsRuntimeDlls(
         os.path.join(chrome_src, GetOutputDirectory()),
         (x86_runtime, x64_runtime))
 
   sys.exit(gyp_rc)