Improve pyautolib errors.

chrome/test/functional/tracing/tab_tracker.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.
 
 import uuid
 
 
 class TabTracker(object):
   """Uniquely track tabs within a window.
 
@@ skipping 42 matching lines @@
     self._uuids.append(tab_uuid)
     return tab_uuid
 
   def ReleaseTab(self, tab_uuid):
     """Release and close a tab tracked by this TabTracker.
 
     Args:
       tab_uuid: the uuid of the tab to close
     """
     idx = self.GetTabIndex(tab_uuid)
-    self._browser.GetBrowserWindow(self._window_idx).GetTab(idx).Close()
+    self._browser.CloseTab(tab_index=idx, windex=self._window_idx)
     del self._uuids[idx]
 
   def GetTabIndex(self, tab_uuid):
     """Get the index of a tracked tab within this TabTracker's window.
 
     Args:
       tab_uuid: the uuid of the tab to close
 
     Returns:
       the index of the tab within this TabTracker's window
     """
     return self._uuids.index(tab_uuid)
 
   def GetWindowIndex(self):
     """Get the index of this TabTracker's window.
 
     Returns:
       the index of this TabTracker's window
     """
     return self._window_idx