deps2git: Add support for overriding DEPS vars

deps_utils.py

 #!/usr/bin/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.
 
 """Utilities for formatting and writing DEPS files."""
 
 import errno
 import os
 import shutil
 import subprocess
 import sys
 import time
 
 
 class VarImpl(object):
   """Implement the Var function used within the DEPS file."""
 
-  def __init__(self, local_scope):
+  def __init__(self, local_scope, var_overrides=None):
     self._local_scope = local_scope
+    self._var_overrides = var_overrides or {}
 
   def Lookup(self, var_name):
     """Implements the Var syntax."""
+    if var_name in self._var_overrides:
+      return self._var_overrides[var_name]
     if var_name in self._local_scope.get('vars', {}):
       return self._local_scope['vars'][var_name]
     raise Exception('Var is not defined: %s' % var_name)
 
 
-def GetDepsContent(deps_path):
+def GetDepsContent(deps_path, var_overrides=None):
   """Read a DEPS file and return all the sections."""
   deps_file = open(deps_path, 'rU')
+  var_overrides = var_overrides or {}
   content = deps_file.read()
   local_scope = {}
-  var = VarImpl(local_scope)
+  var = VarImpl(local_scope, var_overrides)
   global_scope = {
       'Var': var.Lookup,
       'deps': {},
       'deps_os': {},
       'include_rules': [],
       'skip_child_includes': [],
       'hooks': [],
       'vars': {},
   }
   exec(content, global_scope, local_scope)
   local_scope.setdefault('deps', {})
   local_scope.setdefault('deps_os', {})
   local_scope.setdefault('include_rules', [])
   local_scope.setdefault('skip_child_includes', [])
   local_scope.setdefault('hooks', [])
   local_scope.setdefault('vars', {})
+  local_scope['vars'].update(var_overrides)
 
   return (local_scope['deps'], local_scope['deps_os'],
           local_scope['include_rules'], local_scope['skip_child_includes'],
           local_scope['hooks'], local_scope['vars'])
 
 
 def PrettyDeps(deps, indent=0):
   """Stringify a deps dictionary in a pretty way."""
   pretty = ' ' * indent
   pretty += '{\n'
@@ skipping 146 matching lines @@
     # For POSIX:  making the directory writable guarantees removability.
     # Windows will ignore the non-read-only bits in the chmod value.
     os.chmod(root, 0770)
     for name in files:
       remove_with_retry(os.remove, os.path.join(root, name))
     for name in dirs:
       remove_with_retry(lambda p: shutil.rmtree(p, onerror=RmTreeOnError),
                         os.path.join(root, name))
 
   remove_with_retry(os.rmdir, file_path)