Refactor chromedriver's script execution to reduce amount of custom Value parsing.

chrome/test/webdriver/webdriver_util_unittest.cc

 // 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.
 
 #include <set>
 #include <string>
 
-#include "chrome/test/webdriver/utility_functions.h"
+#include "chrome/test/webdriver/webdriver_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 TEST(RandomIDTest, CanGenerateSufficientlyRandomIDs) {
   std::set<std::string> generated_ids;
   for (int i = 0; i < 10000; ++i) {
     std::string id = webdriver::GenerateRandomID();
     ASSERT_EQ(32u, id.length());
     ASSERT_TRUE(generated_ids.end() == generated_ids.find(id))
         << "Generated duplicate ID: " << id
         << " on iteration " << i;
     generated_ids.insert(id);
   }
 }