Support startup performance tests on Galaxy S3

build/android/pylib/perf_tests_helper.py

Index: build/android/pylib/perf_tests_helper.py
diff --git a/build/android/pylib/perf_tests_helper.py b/build/android/pylib/perf_tests_helper.py
index bec92a20d2a1bcb308322ba658d08b5c7e304692..09adf918d0a8e2840671bb7fd228c3769844aec3 100644
--- a/build/android/pylib/perf_tests_helper.py
+++ b/build/android/pylib/perf_tests_helper.py
@@ -133,15 +133,13 @@ class PerfTestSetup(object):
     num_cpus = self._adb.GetFileContents('/sys/devices/system/cpu/online',
                                          log_result=False)
     assert num_cpus, 'Unable to find /sys/devices/system/cpu/online'
-    self._num_cpus = int(num_cpus[0].split('-')[-1])
+    self._num_cpus = int(re.findall(r'\d+', num_cpus[0])[-1])
     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.RunShellCommand('su -c echo 3 > ' + PerfTestSetup._DROP_CACHES)
 
   def SetUp(self):
     """Sets up performance tests."""