Implement cpu_stats for cros backend

BUG=286655

Review URL: https://chromiumcodereview.appspot.com/23902020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222237 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/core/platform/cros_platform_backend.py

@@ -40,6 +40,14 @@ class CrosPlatformBackend(platform_backend.PlatformBackend):
     meminfo_contents = self._GetFileContents('/proc/meminfo')
     return proc_util.GetSystemCommitCharge(meminfo_contents)
 
+  def GetCpuStats(self, pid):
+    stats = self._GetFileContents('/proc/%s/stat' % pid).split()
+    return proc_util.GetCpuStats(stats)
+
+  def GetCpuTimestamp(self):
+    timer_list = self._GetFileContents('/proc/timer_list')
+    return proc_util.GetTimestampJiffies(timer_list)
+
   def GetMemoryStats(self, pid):
     status = self._GetFileContents('/proc/%s/status' % pid)
     stats = self._GetFileContents('/proc/%s/stat' % pid).split()