[Android] Switch to DeviceUtils versions of file functions.

build/android/pylib/perf/perf_control_unittest.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.
 # pylint: disable=W0212
 
 import os
 import sys
 import unittest
 
 sys.path.append(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir))
@@ skipping 12 matching lines @@
     self._device = device_utils.DeviceUtils(
         android_commands.AndroidCommands(device=devices[0]))
 
   def testHighPerfMode(self):
     perf = perf_control.PerfControl(self._device)
     try:
       perf.SetPerfProfilingMode()
       for cpu in range(perf._num_cpu_cores):
         path = perf_control.PerfControl._CPU_ONLINE_FMT % cpu
         self.assertEquals('1',
-                          self._device.old_interface.GetFileContents(path)[0])
+                          self._device.ReadFile(path)[0])
         path = perf_control.PerfControl._SCALING_GOVERNOR_FMT % cpu
         self.assertEquals('performance',
-                          self._device.old_interface.GetFileContents(path)[0])
+                          self._device.ReadFile(path)[0])
     finally:
       perf.SetDefaultPerfMode()
 
 if __name__ == '__main__':
   unittest.main()