Support startup performance tests on Galaxy S3

build/android/pylib/perf_tests_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.
 
 import re
 
 import android_commands
 import json
 import math
 
@@ skipping 124 matching lines @@
   def __init__(self, adb):
     self._adb = adb
     kernel_max = self._adb.GetFileContents('/sys/devices/system/cpu/kernel_max',
                                          log_result=False)
     assert kernel_max, 'Unable to find /sys/devices/system/cpu/kernel_max'
     self._kernel_max = int(kernel_max[0])
     self._original_scaling_governor = None
 
   def DropRamCaches(self):
     """Drops the filesystem ram caches for performance testing."""
-    if not self._adb.IsRootEnabled():
-      self._adb.EnableAdbRoot()
-    self._adb.RunShellCommand('sync')
-    self._adb.RunShellCommand('echo 3 > ' + PerfTestSetup._DROP_CACHES)
+    self._adb.RunShellCommand('su -c sync')
+    self._adb.SetProtectedFileContents(PerfTestSetup._DROP_CACHES, '3')
 
   def SetUp(self):
     """Sets up performance tests."""
     if not self._original_scaling_governor:
       self._original_scaling_governor = self._adb.GetFileContents(
           PerfTestSetup._SCALING_GOVERNOR_FMT % 0,
           log_result=False)[0]
       self._SetScalingGovernorInternal('performance')
     self.DropRamCaches()
 
   def TearDown(self):
     """Tears down performance tests."""
     if self._original_scaling_governor:
       self._SetScalingGovernorInternal(self._original_scaling_governor)
     self._original_scaling_governor = None
 
   def _SetScalingGovernorInternal(self, value):
     for cpu in range(self._kernel_max + 1):
       scaling_governor_file = PerfTestSetup._SCALING_GOVERNOR_FMT % cpu
-      if self._adb.Adb().DoesFileExist(scaling_governor_file):
-        self._adb.RunShellCommand(
-            ('echo %s > ' + scaling_governor_file) % value)
+      if self._adb.FileExistsOnDevice(scaling_governor_file):
+        self._adb.SetProtectedFileContents(scaling_governor_file, value)