Support for TakeScreenshot in cros_platform.

telemetry/telemetry/internal/backends/chrome/cros_browser_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
 
 from telemetry.core import exceptions
 from telemetry.core import util
 from telemetry import decorators
@@ skipping 123 matching lines @@
           # incognito browser in a separate process, which we need to wait for.
           util.WaitFor(lambda: pid != self.pid, 10)
         elif self.browser_options.gaia_login:
           self.oobe.NavigateGaiaLogin(self._username, self._password)
         else:
           self.oobe.NavigateFakeLogin(self._username, self._password,
               self._gaia_id, not self.browser_options.disable_gaia_services)
 
         self._WaitForLogin()
       except exceptions.TimeoutException:
-        self._cri.TakeScreenShot('login-screen')
+        self._cri.TakeScreenshotWithPrefix('login-screen')
         raise exceptions.LoginException('Timed out going through login screen. '
                                         + self._GetLoginStatus())
 
     logging.info('Browser is up!')
 
   def Close(self):
     super(CrOSBrowserBackend, self).Close()
 
     if self._cri:
       self._cri.RestartUI(False) # Logs out.
@@ skipping 70 matching lines @@
     # Wait for cryptohome to mount.
     util.WaitFor(self._IsLoggedIn, 60)
 
     # For incognito mode, the session manager actually relaunches chrome with
     # new arguments, so we have to wait for the browser to come up.
     self._WaitForBrowserToComeUp()
 
     # Wait for extensions to load.
     if self._supports_extensions:
       self._WaitForExtensionsToLoad()