Make landmines work on local builds too

build/vs_toolchain.py

 # Copyright 2014 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.
 
 import json
 import os
 import pipes
 import shutil
 import subprocess
 import sys
@@ skipping 12 matching lines @@
 
 def SetEnvironmentAndGetRuntimeDllDirs():
   """Sets up os.environ to use the depot_tools VS toolchain with gyp, and
   returns the location of the VS runtime DLLs so they can be copied into
   the output directory after gyp generation.
   """
   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:
+    if not os.path.exists(json_data_file):
+      Update()
     with open(json_data_file, 'r') as tempf:
       toolchain_data = json.load(tempf)
 
     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
@@ skipping 140 matching lines @@
       # CopyVsRuntimeDlls via import, currently).
   }
   if len(sys.argv) < 2 or sys.argv[1] not in commands:
     print >>sys.stderr, 'Expected one of: %s' % ', '.join(commands)
     return 1
   return commands[sys.argv[1]]()
 
 
 if __name__ == '__main__':
   sys.exit(main())