Don't run the pre and post handlers after chromedriver receives a termination request.

chrome/test/webdriver/webdriver_session.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_TEST_WEBDRIVER_WEBDRIVER_SESSION_H_
 #define CHROME_TEST_WEBDRIVER_WEBDRIVER_SESSION_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 385 matching lines @@
   Point mouse_position_;
 
   // Chrome does not have an individual method for setting the prompt text
   // of an alert. Instead, when the WebDriver client wants to set the text,
   // we store it here and pass the text when the alert is accepted or
   // dismissed. This text should only be used if |has_alert_prompt_text_|
   // is true, so that the default prompt text is not overridden.
   std::string alert_prompt_text_;
   bool has_alert_prompt_text_;
 
+  // True if the session has started the termination process.
+  bool terminated_;
+
   Options options_;
 
   DISALLOW_COPY_AND_ASSIGN(Session);
 };
 
 }  // namespace webdriver
 
 DISABLE_RUNNABLE_METHOD_REFCOUNT(webdriver::Session);
 
 #endif  // CHROME_TEST_WEBDRIVER_WEBDRIVER_SESSION_H_