[Android] Speculative fix for DeviceUtils.EnableRoot issues.

build/android/pylib/device/device_utils.py

 # Copyright 2014 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.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=unused-argument
 
@@ skipping 272 matching lines @@
     Raises:
       CommandFailedError if root could not be enabled.
       CommandTimeoutError on timeout.
     """
     if self.IsUserBuild():
       raise device_errors.CommandFailedError(
           'Cannot enable root in user builds.', str(self))
     if 'needs_su' in self._cache:
       del self._cache['needs_su']
     self.adb.Root()
-    self.adb.WaitForDevice()
+    self.WaitUntilFullyBooted()
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def IsUserBuild(self, timeout=None, retries=None):
     """Checks whether or not the device is running a user build.
 
     Args:
       timeout: timeout in seconds
       retries: number of retries
 
     Returns:
@@ skipping 1275 matching lines @@
     blacklist = device_blacklist.ReadBlacklist()
     def blacklisted(adb):
       if adb.GetDeviceSerial() in blacklist:
         logging.warning('Device %s is blacklisted.', adb.GetDeviceSerial())
         return True
       return False
 
     return [cls(adb) for adb in adb_wrapper.AdbWrapper.Devices()
             if not blacklisted(adb)]