Set --free-is-write TSan flag default value to "no"....

tools/valgrind/valgrind_test.py

 #!/usr/bin/python
 # Copyright (c) 2006-2008 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.
 
 # valgrind_test.py
 
 """Runs an exe through Valgrind and puts the intermediate files in a
 directory.
 """
@@ skipping 569 matching lines @@
     return True
 
   def ExtendOptionParser(self, parser):
     parser.add_option("", "--hybrid", default="no",
                       dest="hybrid",
                       help="Finds more data races, may give false positive "
                       "reports unless the code is annotated")
     parser.add_option("", "--announce-threads", default="yes",
                       dest="announce_threads",
                       help="Show the the stack traces of thread creation")
+    parser.add_option("", "--free-is-write", default="no",
+                      dest="free_is_write",
+                      help="Treat free()/operator delete as memory write. "
+                      "This helps finding more data races, but (currently) "
+                      "this may give false positive reports on std::string "
+                      "internals, see http://code.google.com/p/data-race-test"
+                      "/issues/detail?id=40")
 
   def EvalBoolFlag(self, flag_value):
     if (flag_value in ["1", "true", "yes"]):
       return True
     elif (flag_value in ["0", "false", "no"]):
       return False
     raise RuntimeError, "Can't parse flag value (%s)" % flag_value
 
   def ToolSpecificFlags(self):
     ret = []
@@ skipping 15 matching lines @@
 
     # This should shorten filepaths for functions intercepted in TSan.
     ret += ["--file-prefix-to-cut=scripts/tsan/tsan/"]
 
     if self.EvalBoolFlag(self._options.hybrid):
       ret += ["--hybrid=yes"] # "no" is the default value for TSAN
 
     if self.EvalBoolFlag(self._options.announce_threads):
       ret += ["--announce-threads"]
 
+    if self.EvalBoolFlag(self._options.free_is_write):
+      ret += ["--free-is-write=yes"]
+    else:
+      ret += ["--free-is-write=no"]
+
+
     # --show-pc flag is needed for parsing the error logs on Darwin.
     if platform_suffix == 'mac':
       ret += ["--show-pc=yes"]
 
     # Don't show googletest frames in stacks.
     ret += ["--cut_stack_below=testing*Test*Run*"]
 
     return ret
 
 class ThreadSanitizerPosix(ThreadSanitizerBase, ValgrindTool):
@@ skipping 168 matching lines @@
 
 if __name__ == "__main__":
   if sys.argv.count("-v") > 0 or sys.argv.count("--verbose") > 0:
     logging_utils.config_root(logging.DEBUG)
   else:
     logging_utils.config_root()
   # TODO(timurrrr): valgrind tools may use -v/--verbose as well
 
   ret = RunTool(sys.argv)
   sys.exit(ret)