Remove all unused variables.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/breakpad/dump_reader.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 42 matching lines @@
             self._host.filesystem.rmtree(self.crash_dumps_directory())
 
     def look_for_new_crash_logs(self, crashed_processes, start_time):
         if not crashed_processes:
             return None
 
         if not self.check_is_functional():
             return None
 
         pid_to_minidump = dict()
-        for root, dirs, files in self._host.filesystem.walk(self.crash_dumps_directory()):
+        for root, _, files in self._host.filesystem.walk(self.crash_dumps_directory()):
             for dmp in [f for f in files if f.endswith(self._file_extension())]:
                 dmp_file = self._host.filesystem.join(root, dmp)
                 if self._host.filesystem.mtime(dmp_file) < start_time:
                     continue
                 pid = self._get_pid_from_dump(dmp_file)
                 if pid:
                     pid_to_minidump[pid] = dmp_file
 
         result = dict()
-        for test, process_name, pid in crashed_processes:
+        for test, _, pid in crashed_processes:
             if str(pid) in pid_to_minidump:
                 stack = self._get_stack_from_dump(pid_to_minidump[str(pid)])
                 if stack:
                     result[test] = stack
 
         return result
 
     def _get_pid_from_dump(self, dump_file):
         """This routine must be implemented by subclasses.
 
         This routine returns the PID of the crashed process that produced the given dump_file."""
         raise NotImplementedError()
 
     def _get_stack_from_dump(self, dump_file):
         """This routine must be implemented by subclasses.
 
         Returns the stack stored in the given breakpad dump_file."""
         raise NotImplementedError()
 
     def _file_extension(self):
         """This routine must be implemented by subclasses.
 
         Returns the file extension of crash dumps written by breakpad."""
         raise NotImplementedError()