[Android] Move some pylib modules into devil/

build/android/devil/utils/cmd_helper.py

 # 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.
 
 """A wrapper for subprocess to make calling shell commands easier."""
 
 import logging
 import os
 import pipes
 import select
@@ skipping 270 matching lines @@
     buffer_output += data
     has_incomplete_line = buffer_output[-1] not in '\r\n'
     lines = buffer_output.splitlines()
     buffer_output = lines.pop() if has_incomplete_line else ''
     for line in lines:
       yield line
   if buffer_output:
     yield buffer_output
   if check_status and process.returncode:
     raise subprocess.CalledProcessError(process.returncode, cmd)