Do not reboot emulator.

build/android/buildbot/bb_device_steps.py

 #!/usr/bin/env python
 # Copyright (c) 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 collections
 import glob
 import multiprocessing
 import os
 import shutil
@@ skipping 66 matching lines @@
   except errors.DeviceUnresponsiveError as e:
     return e
 
 
 def RebootDevices():
   """Reboot all attached and online devices."""
   # Early return here to avoid presubmit dependence on adb,
   # which might not exist in this checkout.
   if bb_utils.TESTING:
     return
-  devices = android_commands.GetAttachedDevices()
+  devices = android_commands.GetAttachedDevices(emulator=False)
   print 'Rebooting: %s' % devices
   if devices:
     pool = multiprocessing.Pool(len(devices))
     results = pool.map_async(RebootDeviceSafe, devices).get(99999)
 
     for device, result in zip(devices, results):
       if result:
         print '%s failed to startup.' % device
 
     if any(results):
@@ skipping 285 matching lines @@
     return sys.exit('Unknown tests %s' % list(unknown_tests))
 
   setattr(options, 'target', options.factory_properties.get('target', 'Debug'))
 
   MainTestWrapper(options)
   provision_devices.KillHostHeartbeat()
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))