[Android] Fix new pylint errors in build/android/.

build/android/symbolize.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.
 
 """Symbolizes stack traces generated by Chromium for Android.
 
 Sample usage:
   adb logcat chromium:V | symbolize.py
 """
 
 import os
 import re
 import sys
 
 from pylib import constants
 
 # Uses symbol.py from third_party/android_platform, not python's.
 sys.path.insert(0,
                 os.path.join(constants.DIR_SOURCE_ROOT,
                             'third_party/android_platform/development/scripts'))
 import symbol
 
 # Sample output from base/debug/stack_trace_android.cc
 #00 0x693cd34f /path/to/some/libfoo.so+0x0007434f
-TRACE_LINE = re.compile('(?P<frame>\#[0-9]+ 0x[0-9a-f]{8,8}) '
-                        '(?P<lib>[^+]+)\+0x(?P<addr>[0-9a-f]{8,8})')
+TRACE_LINE = re.compile(r'(?P<frame>\#[0-9]+ 0x[0-9a-f]{8,8}) '
+                        r'(?P<lib>[^+]+)\+0x(?P<addr>[0-9a-f]{8,8})')
 
 class Symbolizer(object):
   def __init__(self, output):
     self._output = output
 
   def write(self, data):
     while True:
       match = re.search(TRACE_LINE, data)
       if not match:
         self._output.write(data)
@@ skipping 40 matching lines @@
 
 def main():
   symbolizer = Symbolizer(sys.stdout)
   for line in sys.stdin:
     symbolizer.write(line)
   symbolizer.flush()
 
 
 if __name__ == '__main__':
   main()