Improve pyautolib errors.

chrome/test/functional/webrtc_brutality_test.py

 #!/usr/bin/env python
 # 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.
 
 import pyauto_functional
 import webrtc_test_base
 
 
 class WebrtcBrutalityTest(webrtc_test_base.WebrtcTestBase):
@@ skipping 39 matching lines @@
     self.NavigateToURL(url)
 
     self.GetUserMedia(tab_index=0, action='allow')
     self.ReloadTab(tab_index=0)
 
   def testClosingTabAfterGetUserMedia(self):
     """Tests closing the tab right after a getUserMedia call."""
     url = self.GetFileURLForDataPath('webrtc', 'webrtc_jsep_test.html')
     self.NavigateToURL(url)
 
-    tab = self.GetBrowserWindow(0).GetTab(0)
     self._GetUserMediaWithoutTakingAction(tab_index=0)
-    tab.Close()
+    self.CloseTab()
 
   def testSuccessfulGetUserMediaAndThenClose(self):
     """Waits for WebRTC to respond, and closes the tab."""
     url = self.GetFileURLForDataPath('webrtc', 'webrtc_jsep_test.html')
     self.NavigateToURL(url)
 
-    tab = self.GetBrowserWindow(0).GetTab(0)
     self.GetUserMedia(tab_index=0, action='allow')
-    tab.Close()
+    self.CloseTab()
 
   def _GetUserMediaWithoutTakingAction(self, tab_index):
     self.assertEquals('ok-requested', self.ExecuteJavascript(
       'getUserMedia(true, true)', tab_index=0))
 
 
 if __name__ == '__main__':
-  pyauto_functional.Main()
+  pyauto_functional.Main()