[NaCl SDK] Allow dsc files to omit TOOLS setting

native_client_sdk/src/build_tools/parse_dsc.py

 #!/usr/bin/env python
 # Copyright (c) 2013 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 argparse
 import collections
 import fnmatch
 import os
 import sys
@@ skipping 10 matching lines @@
 
 # 'KEY' : ( <TYPE>, [Accepted Values], <Required?>)
 DSC_FORMAT = {
     'DISABLE': (bool, [True, False], False),
     'SEL_LDR': (bool, [True, False], False),
     # Disable this project from being included in the NaCl packaged app.
     'DISABLE_PACKAGE': (bool, [True, False], False),
     # Don't generate the additional files to allow this project to run as a
     # packaged app (i.e. manifest.json, background.js, etc.).
     'NO_PACKAGE_FILES': (bool, [True, False], False),
-    'TOOLS' : (list, VALID_TOOLCHAINS, True),
+    'TOOLS' : (list, VALID_TOOLCHAINS, False),
     'CONFIGS' : (list, ['Debug', 'Release'], False),
     'PREREQ' : (list, '', False),
     'TARGETS' : (list, {
         'NAME': (str, '', True),
         # main = nexe target
         # lib = library target
         # so = shared object target, automatically added to NMF
         # so-standalone =  shared object target, not put into NMF
         'TYPE': (str, ['main', 'lib', 'static-lib', 'so', 'so-standalone'],
                  True),
@@ skipping 118 matching lines @@
 def LoadProject(filename):
   with open(filename, 'r') as descfile:
     try:
       desc = eval(descfile.read(), {}, {})
     except Exception as e:
       raise ValidationError(e)
   if desc.get('DISABLE', False):
     return None
   ValidateFormat(desc, DSC_FORMAT)
   desc['FILEPATH'] = os.path.abspath(filename)
+  desc.setdefault('TOOLS', VALID_TOOLCHAINS)
   return desc
 
 
 def LoadProjectTreeUnfiltered(srcpath):
   # Build the tree
   out = collections.defaultdict(list)
   for root, _, files in os.walk(srcpath):
     for filename in files:
       if fnmatch.fnmatch(filename, '*.dsc'):
         filepath = os.path.join(root, filename)
@@ skipping 87 matching lines @@
   except ValidationError as e:
     sys.stderr.write(str(e) + '\n')
     return 1
 
   PrintProjectTree(tree)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))