Android: further "user build" perf test automation.

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 711 matching lines @@
         self.GetExternalStorage() + '/' + base_name % i):
       i += 1
     return self.GetExternalStorage() + '/' + base_name % i
 
   def CanAccessProtectedFileContents(self):
     """Returns True if Get/SetProtectedFileContents would work via "su".
 
     Devices running user builds don't have adb root, but may provide "su" which
     can be used for accessing protected files.
     """
-    return self.RunShellCommand('su -c echo') == ['']
+    return self.RunShellCommand('su -c cat /dev/null') == ['']

[Sami, 2013/02/13 11:05:34]

This could be slightly more reliable if we tried to cat a file that was only
readable by root (e.g., /proc/kmsg). But let's not make this any more complex
than it needs to be :)

[bulach, 2013/02/13 11:08:57]

:)

 
   def GetProtectedFileContents(self, filename, log_result=False):
     """Gets contents from the protected file specified by |filename|.
 
     This is less efficient than GetFileContents, but will work for protected
     files and device files.
     """
     # Run the script as root
     return self.RunShellCommand('su -c cat "%s" 2> /dev/null' % filename)
 
@@ skipping 474 matching lines @@
   """
   def __init__(self, output):
     self._output = output
 
   def write(self, data):
     data = data.replace('\r\r\n', '\n')
     self._output.write(data)
 
   def flush(self):
     self._output.flush()