Document that the user has to run `adb root` to enable java asserts.

build/android/pylib/instrumentation/test_runner.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.
 
 """Class for running instrumentation tests on a single device."""
 
 import collections
 import logging
 import os
 import re
@@ skipping 79 matching lines @@
   def _TakeScreenshot(self, test):
     """Takes a screenshot from the device."""
     screenshot_name = os.path.join(constants.SCREENSHOTS_DIR, '%s.png' % test)
     logging.info('Taking screenshot named %s', screenshot_name)
     self.device.TakeScreenshot(screenshot_name)
 
   def SetUp(self):
     """Sets up the test harness and device before all tests are run."""
     super(TestRunner, self).SetUp()
     if not self.device.HasRoot():
-      logging.warning('Unable to enable java asserts for %s, non rooted device',
+      logging.warning('Unable to enable java asserts for %s; run `adb root`.',
                       str(self.device))
     else:
       if self.device.SetJavaAsserts(self.options.set_asserts):
         self.device.RunShellCommand('stop')
         self.device.RunShellCommand('start')
         self.device.WaitUntilFullyBooted()
 
     # We give different default value to launch HTTP server based on shard index
     # because it may have race condition when multiple processes are trying to
     # launch lighttpd with same port at same time.
@@ skipping 300 matching lines @@
             result_name, ' '.join(flag_modifiers.add))
         if flag_modifiers.remove:
           result_name = '%s without {%s}' % (
             result_name, ' '.join(flag_modifiers.remove))
         result.SetName(result_name)
       results.AddResult(result)
 
       self.TestTeardown(test, results)
 
     return (results, None if results.DidRunPass() else test)