Fix calls to ls /root that might be empty

build/android/pylib/android_commands.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.
 
 """Provides an interface to communicate with the device via the adb command.
 
 Assumes adb binary is currently on system path.
 """
 
 import collections
@@ skipping 205 matching lines @@
 
   Args:
     device: If given, adb commands are only send to the device of this ID.
         Otherwise commands are sent to all attached devices.
   """
 
   def __init__(self, device=None):
     self._adb = adb_interface.AdbInterface()
     if device:
       self._adb.SetTargetSerial(device)
-    root_test_output = self.RunShellCommand('ls /root')[0]
-    self._root_enabled = not 'Permission denied' in root_test_output
     self._logcat = None
     self._original_governor = None
     self._pushed_files = []
     self._device_utc_offset = self.RunShellCommand('date +%z')[0]
 
   def Adb(self):
     """Returns our AdbInterface to avoid us wrapping all its methods."""
     return self._adb
 
-  def EnableAdbRoot(self):
-    self._root_enabled = self.Adb().EnableAdbRoot()
-    self._adb.SendCommand('wait-for-device')
-
   def IsRootEnabled(self):
-    """Returns whether or not _adb.EnabledAdbRoot() has succeeded."""
-    return self._root_enabled
+    """Checks if root is enabled on the device."""
+    root_test_output = self.RunShellCommand('ls /root') or ['']
+    return not 'Permission denied' in root_test_output[0]
 
   def GetDeviceYear(self):
     """Returns the year information of the date on device."""
     return self.RunShellCommand('date +%Y')[0]
 
   def WaitForDevicePm(self):
     """Blocks until the device's package manager is available.
 
     To workaround http://b/5201039, we restart the shell and retry if the
     package manager isn't back after 120 seconds.
@@ skipping 730 matching lines @@
           if len(process_results) <= 8:
             continue
           # Column 0 is the executable name
           # Column 1 is the pid
           # Column 8 is the Inode in use
           if process_results[8] == socket_name:
             pids.append((int(process_results[1]), process_results[0]))
         break
     logging.info('PidsUsingDevicePort: %s', pids)
     return pids