Remove kChildCleanExit since it's not used anymore.

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 747 matching lines @@
   def ExtraChromeFlags(self):
     """Ensures Chrome is launched with custom flags.
 
     Returns:
       A list of extra flags to pass to Chrome when it is launched.
     """
     flags = super(BasePerfTest, self).ExtraChromeFlags()
     # Window size impacts a variety of perf tests, ensure consistency.
     flags.append('--window-size=1024,768')
     if self._IsPGOMode():
-      flags = flags + ['--child-clean-exit', '--no-sandbox']
+      flags = flags + ['--no-sandbox']
     return flags
 
 
 class TabPerfTest(BasePerfTest):
   """Tests that involve opening tabs."""
 
   def testNewTab(self):
     """Measures time to open a new tab."""
     self._RunNewTabTest('NewTabPage',
                         lambda: self._AppendTab('chrome://newtab'), 'open_tab')
@@ skipping 1638 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()