[Telemetry] Assert that android devices are rooted when running telemetry.

telemetry/telemetry/internal/platform/android_platform_backend.py

 # Copyright 2013 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 logging
 import os
 import posixpath
 import re
 import subprocess
 import tempfile
@@ skipping 60 matching lines @@
     assert device, (
         'AndroidPlatformBackend can only be initialized from remote device')
     super(AndroidPlatformBackend, self).__init__(device)
     self._device = device_utils.DeviceUtils(device.device_id)
     # Trying to root the device, if possible.
     if not self._device.HasRoot():
       try:
         self._device.EnableRoot()
       except device_errors.CommandFailedError:
         logging.warning('Unable to root %s', str(self._device))
+    assert self._device.HasRoot(), (
+        'Android device must be rooted to run Telemetry')
     self._battery = battery_utils.BatteryUtils(self._device)
     self._enable_performance_mode = device.enable_performance_mode
     self._surface_stats_collector = None
     self._perf_tests_setup = perf_control.PerfControl(self._device)
     self._thermal_throttle = thermal_throttle.ThermalThrottle(self._device)
     self._raw_display_frame_rate_measurements = []
     self._can_elevate_privilege = (
         self._device.HasRoot() or self._device.NeedsSU())
     self._device_copy_script = None
     self._power_monitor = (
@@ skipping 750 matching lines @@
   for process in psutil.process_iter():
     try:
       if psutil.version_info >= (2, 0):
         if 'adb' in process.name():
           process.cpu_affinity([0])
       else:
         if 'adb' in process.name:
           process.set_cpu_affinity([0])
     except (psutil.NoSuchProcess, psutil.AccessDenied):
       logging.warn('Failed to set adb process CPU affinity')