Update from https://crrev.com/306901

build/android/pylib/device/adb_wrapper.py

 # 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.
 
 """This module wraps Android's adb tool.
 
 This is a thin wrapper around the adb interface. Any additional complexity
 should be delegated to a higher level (ex. DeviceUtils).
 """
 
+import collections
 import errno
 import logging
 import os
 
 from pylib import cmd_helper
 from pylib import constants
 from pylib.device import decorators
 from pylib.device import device_errors
 from pylib.utils import timeout_retry
 
 
 _DEFAULT_TIMEOUT = 30
 _DEFAULT_RETRIES = 2
 
 
 def _VerifyLocalFileExists(path):
   """Verifies a local file exists.
 
   Args:
     path: Path to the local file.
 
   Raises:
     IOError: If the file doesn't exist.
   """
   if not os.path.exists(path):
     raise IOError(errno.ENOENT, os.strerror(errno.ENOENT), path)
 
 
+DeviceStat = collections.namedtuple('DeviceStat',
+                                    ['st_mode', 'st_size', 'st_time'])
+
+
 class AdbWrapper(object):
   """A wrapper around a local Android Debug Bridge executable."""
 
   def __init__(self, device_serial):
     """Initializes the AdbWrapper.
 
     Args:
       device_serial: The device serial number as a string.
     """
     if not device_serial:
@@ skipping 144 matching lines @@
       except ValueError:
         logging.warning('exit status of shell command %r missing.', command)
         raise device_errors.AdbCommandFailedError(
             args, output, device_serial=self._device_serial)
       output = output[:output_end]
       if status != expect_status:
         raise device_errors.AdbCommandFailedError(
             args, output, status, self._device_serial)
     return output
 
+  def Ls(self, path, timeout=_DEFAULT_TIMEOUT, retries=_DEFAULT_RETRIES):
+    """List the contents of a directory on the device.
+
+    Args:
+      path: Path on the device filesystem.
+      timeout: (optional) Timeout per try in seconds.
+      retries: (optional) Number of retries to attempt.
+
+    Returns:
+      A list of pairs (filename, stat) for each file found in the directory,
+      where the stat object has the properties: st_mode, st_size, and st_time.
+
+    Raises:
+      AdbCommandFailedError if |path| does not specify a valid and accessible
+          directory in the device.
+    """
+    def ParseLine(line):
+      cols = line.split(None, 3)
+      filename = cols.pop()
+      stat = DeviceStat(*[int(num, base=16) for num in cols])
+      return (filename, stat)
+
+    cmd = ['ls', path]
+    lines = self._RunDeviceAdbCmd(
+        cmd, timeout=timeout, retries=retries).splitlines()
+    if lines:
+      return [ParseLine(line) for line in lines]
+    else:
+      raise device_errors.AdbCommandFailedError(
+          cmd, 'path does not specify an accessible directory in the device',
+          device_serial=self._device_serial)
+
   def Logcat(self, filter_spec=None, timeout=_DEFAULT_TIMEOUT,
              retries=_DEFAULT_RETRIES):
     """Get the logcat output.
 
     Args:
       filter_spec: (optional) Spec to filter the logcat.
       timeout: (optional) Timeout per try in seconds.
       retries: (optional) Number of retries to attempt.
 
     Returns:
@@ skipping 183 matching lines @@
     """Restarts the adbd daemon with root permissions, if possible.
 
     Args:
       timeout: (optional) Timeout per try in seconds.
       retries: (optional) Number of retries to attempt.
     """
     output = self._RunDeviceAdbCmd(['root'], timeout, retries)
     if 'cannot' in output:
       raise device_errors.AdbCommandFailedError(
           ['root'], output, device_serial=self._device_serial)