Refactor gyp_chromium to ease reuse.

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 glob
@@ skipping 328 matching lines @@
 
 
 def GetDesiredVsToolchainHashes():
   """Load a list of SHA1s corresponding to the toolchains that we want installed
   to build with."""
   sha1path = os.path.join(script_dir, 'toolchain_vs2013.hash')
   with open(sha1path, 'rb') as f:
     return f.read().strip().splitlines()
 
 
+def DownloadVsToolChain():
+  """Download the Visual Studio toolchain on Windows.
+
+  If on Windows, request that depot_tools install/update the automatic
+  toolchain, and then use it (unless opted-out) and return a tuple containing
+  the x64 and x86 paths. Otherwise return None.
+  """
+  vs2013_runtime_dll_dirs = None
+  depot_tools_win_toolchain = \
+      bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')))
+  if sys.platform in ('win32', 'cygwin') and depot_tools_win_toolchain:
+    import find_depot_tools
+    depot_tools_path = find_depot_tools.add_depot_tools_to_path()
+    temp_handle, data_file = tempfile.mkstemp(suffix='.json')
+    os.close(temp_handle)
+    get_toolchain_args = [
+        sys.executable,
+        os.path.join(depot_tools_path,
+                    'win_toolchain',
+                    'get_toolchain_if_necessary.py'),
+        '--output-json', data_file,
+      ] + GetDesiredVsToolchainHashes()
+    subprocess.check_call(get_toolchain_args)
+
+    with open(data_file, 'r') as tempf:
+      toolchain_data = json.load(tempf)
+    os.unlink(data_file)
+
+    toolchain = toolchain_data['path']
+    version = toolchain_data['version']
+    version_is_pro = version[-1] != 'e'
+    win8sdk = toolchain_data['win8sdk']
+    wdk = toolchain_data['wdk']
+    # TODO(scottmg): The order unfortunately matters in these. They should be
+    # split into separate keys for x86 and x64. (See CopyVsRuntimeDlls call
+    # below). http://crbug.com/345992
+    vs2013_runtime_dll_dirs = toolchain_data['runtime_dirs']
+
+    os.environ['GYP_MSVS_OVERRIDE_PATH'] = toolchain
+    os.environ['GYP_MSVS_VERSION'] = version
+    # We need to make sure windows_sdk_path is set to the automated
+    # toolchain values in GYP_DEFINES, but don't want to override any
+    # otheroptions.express
+    # values there.
+    gyp_defines_dict = gyp.NameValueListToDict(gyp.ShlexEnv('GYP_DEFINES'))
+    gyp_defines_dict['windows_sdk_path'] = win8sdk
+    os.environ['GYP_DEFINES'] = ' '.join('%s=%s' % (k, pipes.quote(str(v)))
+        for k, v in gyp_defines_dict.iteritems())
+    os.environ['WINDOWSSDKDIR'] = win8sdk
+    os.environ['WDK_DIR'] = wdk
+    # Include the VS runtime in the PATH in case it's not machine-installed.
+    runtime_path = ';'.join(vs2013_runtime_dll_dirs)
+    os.environ['PATH'] = runtime_path + ';' + os.environ['PATH']
+    print('Using automatic toolchain in %s (%s edition).' % (
+              toolchain, 'Pro' if version_is_pro else 'Express'))
+  return vs2013_runtime_dll_dirs
+
+
 def CopyVsRuntimeDlls(output_dir, runtime_dirs):
   """Copies the VS runtime DLLs from the given |runtime_dirs| to the output
   directory so that even if not system-installed, built binaries are likely to
   be able to run.
 
   This needs to be run after gyp has been run so that the expected target
   output directories are already created.
   """
   assert sys.platform.startswith(('win32', 'cygwin'))
 
@@ skipping 102 matching lines @@
   # . set the env var only if it hasn't been set yet
   # . chromium.gyp_env has been applied to os.environ at this point already
   if sys.platform.startswith('linux') and not os.environ.get('GYP_GENERATORS'):
     os.environ['GYP_GENERATORS'] = 'ninja'
   if sys.platform.startswith('win') and not os.environ.get('GYP_GENERATORS'):
     os.environ['GYP_GENERATORS'] = 'ninja'
   elif sys.platform == 'darwin' and not os.environ.get('GYP_GENERATORS') and \
       not 'OS=ios' in os.environ.get('GYP_DEFINES', []):
     os.environ['GYP_GENERATORS'] = 'ninja'
 
-  # If on Windows, request that depot_tools install/update the automatic
-  # toolchain, and then use it (unless opted-out).
-  vs2013_runtime_dll_dirs = None
-  depot_tools_win_toolchain = \
-      bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')))
-  if sys.platform in ('win32', 'cygwin') and depot_tools_win_toolchain:
-    import find_depot_tools
-    depot_tools_path = find_depot_tools.add_depot_tools_to_path()
-    temp_handle, data_file = tempfile.mkstemp(suffix='.json')
-    os.close(temp_handle)
-    get_toolchain_args = [
-        sys.executable,
-        os.path.join(depot_tools_path,
-                    'win_toolchain',
-                    'get_toolchain_if_necessary.py'),
-        '--output-json', data_file,
-      ] + GetDesiredVsToolchainHashes()
-    subprocess.check_call(get_toolchain_args)
-
-    with open(data_file, 'r') as tempf:
-      toolchain_data = json.load(tempf)
-    os.unlink(data_file)
-
-    toolchain = toolchain_data['path']
-    version = toolchain_data['version']
-    version_is_pro = version[-1] != 'e'
-    win8sdk = toolchain_data['win8sdk']
-    wdk = toolchain_data['wdk']
-    # TODO(scottmg): The order unfortunately matters in these. They should be
-    # split into separate keys for x86 and x64. (See CopyVsRuntimeDlls call
-    # below). http://crbug.com/345992
-    vs2013_runtime_dll_dirs = toolchain_data['runtime_dirs']
-
-    os.environ['GYP_MSVS_OVERRIDE_PATH'] = toolchain
-    os.environ['GYP_MSVS_VERSION'] = version
-    # We need to make sure windows_sdk_path is set to the automated
-    # toolchain values in GYP_DEFINES, but don't want to override any
-    # otheroptions.express
-    # values there.
-    gyp_defines_dict = gyp.NameValueListToDict(gyp.ShlexEnv('GYP_DEFINES'))
-    gyp_defines_dict['windows_sdk_path'] = win8sdk
-    os.environ['GYP_DEFINES'] = ' '.join('%s=%s' % (k, pipes.quote(str(v)))
-        for k, v in gyp_defines_dict.iteritems())
-    os.environ['WINDOWSSDKDIR'] = win8sdk
-    os.environ['WDK_DIR'] = wdk
-    # Include the VS runtime in the PATH in case it's not machine-installed.
-    runtime_path = ';'.join(vs2013_runtime_dll_dirs)
-    os.environ['PATH'] = runtime_path + ';' + os.environ['PATH']
-    print('Using automatic toolchain in %s (%s edition).' % (
-              toolchain, 'Pro' if version_is_pro else 'Express'))
+  vs2013_runtime_dll_dirs = DownloadVsToolChain()
 
   # If CHROMIUM_GYP_SYNTAX_CHECK is set to 1, it will invoke gyp with --check
   # to enfore syntax checking.
   syntax_check = os.environ.get('CHROMIUM_GYP_SYNTAX_CHECK')
   if syntax_check and int(syntax_check):
     args.append('--check')
 
   supplemental_includes = GetSupplementalFiles()
   gn_vars_dict = GetGypVarsForGN(supplemental_includes)
 
@@ skipping 24 matching lines @@
   print 'Running build/landmines.py...'
   subprocess.check_call(
       [sys.executable, os.path.join(script_dir, 'landmines.py')])
 
   if vs2013_runtime_dll_dirs:
     x64_runtime, x86_runtime = vs2013_runtime_dll_dirs
     CopyVsRuntimeDlls(os.path.join(chrome_src, GetOutputDirectory()),
                       (x86_runtime, x64_runtime))
 
   sys.exit(gyp_rc)