Revert r144460 "Remove the linux-only CR_SOURCE_ROOT environment variable override of base::DIR_SOU…

testing/test_env.py

 #!/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.
 
 """Sets environment variables needed to run a chromium unit test."""
 
 import os
 import subprocess
 import sys
 
 # This is hardcoded to be src/ relative to this script.
 ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 
 
 def fix_python_path(cmd):
   """Returns the fixed command line to call the right python executable."""
   out = cmd[:]
   if out[0] == 'python':
     out[0] = sys.executable
   elif out[0].endswith('.py'):
     out.insert(0, sys.executable)
   return out
 
 
 def run_executable(cmd, env):
   """Runs an executable with:
+    - environment variable CR_SOURCE_ROOT set to the root directory.
     - environment variable LANGUAGE to en_US.UTF-8.
     - Reuses sys.executable automatically.
   """
   # Many tests assume a English interface...
   env['LANGUAGE'] = 'en_US.UTF-8'
+  # Used by base/base_paths_linux.cc as an override. Just make sure the default
+  # logic is used.
+  env.pop('CR_SOURCE_ROOT', None)
   # Ensure paths are correctly separated on windows.
   cmd[0] = cmd[0].replace('/', os.path.sep)
   cmd = fix_python_path(cmd)
   try:
     return subprocess.call(cmd, env=env)
   except OSError:
     print >> sys.stderr, 'Failed to start %s' % cmd
     raise
 
 
 def main():
   return run_executable(sys.argv[1:], os.environ.copy())
 
 
 if __name__ == "__main__":
   sys.exit(main())