[Android] Sever findbugs dependencies on environment variables.

build/android/findbugs_diff.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.
 
 """Runs findbugs, and returns an error code if there are new warnings.
 This runs findbugs with an additional flag to exclude known bugs.
 To update the list of known bugs, do this:
 
@@ skipping 10 matching lines @@
 
 Run
   $CHROM_SRC/third_party/findbugs/bin/findbugs -textui for details.
 
 """
 
 import optparse
 import os
 import sys
 
-from pylib import findbugs
+from pylib import constants
+from pylib.utils import findbugs
 
 
 def main(argv):
-  if not findbugs.CheckEnvironment():
-    return 1
-
   parser = findbugs.GetCommonParser()
 
   options, _ = parser.parse_args()
 
-  chrome_src = os.getenv('CHROME_SRC')
-
   if not options.base_dir:
-    options.base_dir = os.path.join(chrome_src, 'build', 'android',
+    options.base_dir = os.path.join(constants.CHROME_DIR, 'build', 'android',
                                     'findbugs_filter')
   if not options.only_analyze:
     options.only_analyze = 'org.chromium.-'
 
   return findbugs.Run(options)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))