Fix bug in pyauto perf tests where list containing result 0 isn't handled properly.

chrome/test/functional/perf.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.
 
 """Basic pyauto performance tests.
 
 For tests that need to be run for multiple iterations (e.g., so that average
 and standard deviation values can be reported), the default number of iterations
 run for each of these tests is specified by |_DEFAULT_NUM_ITERATIONS|.
@@ skipping 358 matching lines @@
           the |units_x| argument must also be specified.
       units: A string representing the units of the performance measurement(s).
           Should not include spaces.
       graph_name: A string name for the graph associated with this performance
           value.  Only used on Chrome desktop.
       units_x: A string representing the units of the x-axis values associated
           with the performance measurements, such as 'iteration' if the x values
           are iteration numbers.  If this argument is specified, then the
           |value| argument must be a list of (x, y) tuples.
     """
-    if isinstance(value, list) and value[0] and isinstance(value[0], tuple):
+    if (isinstance(value, list) and value[0] is not None and
+        isinstance(value[0], tuple)):
       assert units_x
     if units_x:
       assert isinstance(value, list)
 
     if self.IsChromeOS():
       # ChromeOS results don't support lists.
-      if (isinstance(value, list) and value[0] and
+      if (isinstance(value, list) and value[0] is not None and
           not isinstance(value[0], tuple)):
         value = Mean(value)
 
       if units_x:
         # TODO(dennisjeffrey): Support long-running performance measurements on
         # ChromeOS in a way that can be graphed: crosbug.com/21881.
         pyauto_utils.PrintPerfResult(graph_name, description, value,
                                      units + ' ' + units_x)
       else:
         # Output short-running performance results in a format understood by
@@ skipping 2112 matching lines @@
     """Identifies the port number to which the server is currently bound.
 
     Returns:
       The numeric port number to which the server is currently bound.
     """
     return self._server.server_address[1]
 
 
 if __name__ == '__main__':
   pyauto_functional.Main()