[Android] Refactor md5_check + add tests

build/android/gyp/javac.py

 #!/usr/bin/env python
 #
 # Copyright 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 fnmatch
 import optparse
 import os
 import sys
@@ skipping 34 matching lines @@
       'javac',
       '-g',
       '-source', '1.5',
       '-target', '1.5',
       '-classpath', ':'.join(classpath),
       '-d', output_dir,
       '-Xlint:unchecked',
       '-Xlint:deprecation',
       ] + java_files
 
-  md5_stamp = '%s/javac.md5' % options.output_dir
-  md5_checker = md5_check.Md5Checker(
-      stamp=md5_stamp,
-      inputs=java_files + jar_inputs,
-      command=javac_cmd)
-  if md5_checker.IsStale():
+  def Compile():
     # Delete the classes directory. This ensures that all .class files in the
     # output are actually from the input .java files. For example, if a .java
     # file is deleted or an inner class is removed, the classes directory should
     # not contain the corresponding old .class file after running this action.
     build_utils.DeleteDirectory(output_dir)
     build_utils.MakeDirectory(output_dir)
     suppress_output = not options.chromium_code
     build_utils.CheckCallDie(javac_cmd, suppress_output=suppress_output)
-    md5_checker.Write()
+
+  record_path = '%s/javac.md5.stamp' % options.output_dir
+  md5_check.CallAndRecordIfStale(
+      Compile,
+      record_path=record_path,
+      input_paths=java_files + jar_inputs,
+      input_strings=javac_cmd)
+
 
 def main(argv):
   parser = optparse.OptionParser()
   parser.add_option('--src-dirs', help='Directories containing java files.')
   parser.add_option('--javac-includes',
       help='A list of file patterns. If provided, only java files that match' +
         'one of the patterns will be compiled.')
   parser.add_option('--classpath', help='Classpath for javac.')
   parser.add_option('--output-dir', help='Directory for javac output.')
   parser.add_option('--stamp', help='Path to touch on success.')
   parser.add_option('--chromium-code', type='int', help='Whether code being '
                     'compiled should be built with stricter warnings for '
                     'chromium code.')
 
   # TODO(newt): remove this once http://crbug.com/177552 is fixed in ninja.
   parser.add_option('--ignore', help='Ignored.')
 
   options, _ = parser.parse_args()
 
   DoJavac(options)
 
   if options.stamp:
     build_utils.Touch(options.stamp)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))