devtools: fix unused import and whitespace in `android_shell.py`.

mojo/devtools/common/devtoolslib/android_shell.py

 # Copyright 2014 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 atexit
 import hashlib
-import json
 import logging
 import os
 import os.path
 import random
 import re
 import subprocess
 import sys
 import tempfile
 import threading
 import time
@@ skipping 42 matching lines @@
     if port not in opened:
       return port
   else:
     raise Exception('Failed to identify an available port.')
 
 
 def _find_available_host_port():
   netstat_output = subprocess.check_output(['netstat'])
   return _find_available_port(netstat_output)
 
+
 def parse_adb_devices_output(adb_devices_output):
   """Parses the output of the `adb devices` command, returning a dictionary
   mapping device id to the status of the device, as printed by `adb devices`.
   """
   # Split into lines skipping empty ones.
   lines = [line.strip() for line in adb_devices_output.split('\n')
            if line.strip()]
 
   if _ADB_DEVICES_HEADER not in lines:
     return None
@@ skipping 391 matching lines @@
           Results.output = rf.read()
 
     run_thread = threading.Thread(target=do_run)
     run_thread.start()
     run_thread.join(timeout)
 
     if run_thread.is_alive():
       self.stop_shell()
       return None, Results.output, True
     return None, Results.output, False