Improve pyautolib errors.

chrome/test/functional/webrtc_brutality_test.py

Index: chrome/test/functional/webrtc_brutality_test.py
diff --git a/chrome/test/functional/webrtc_brutality_test.py b/chrome/test/functional/webrtc_brutality_test.py
index be115bcbbdf3bcd9a0a51cabf22461a888b85ce2..b095354cdf3aa11dc881bd7eb87998f0e6dcc5ce 100755
--- a/chrome/test/functional/webrtc_brutality_test.py
+++ b/chrome/test/functional/webrtc_brutality_test.py
@@ -57,18 +57,16 @@ class WebrtcBrutalityTest(webrtc_test_base.WebrtcTestBase):
     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(
@@ -76,4 +74,4 @@ class WebrtcBrutalityTest(webrtc_test_base.WebrtcTestBase):
 
 
 if __name__ == '__main__':
-  pyauto_functional.Main()
+  pyauto_functional.Main()