Use a direct include of strings headers in chrome/installer/, part 2.

chrome/installer/util/product_operations.h

 // 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.
 
 #ifndef CHROME_INSTALLER_UTIL_PRODUCT_OPERATIONS_H_
 #define CHROME_INSTALLER_UTIL_PRODUCT_OPERATIONS_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "chrome/installer/util/shell_util.h"
 #include "chrome/installer/util/util_constants.h"
 
 class BrowserDistribution;
 class CommandLine;
 
 namespace installer {
 
 class ChannelInfo;
 class MasterPreferences;
@@ skipping 65 matching lines @@
   // sets the wheels in motion or in simple cases does the experiment itself.
   virtual void LaunchUserExperiment(const base::FilePath& setup_path,
                                     const std::set<string16>& options,
                                     InstallStatus status,
                                     bool system_level) const = 0;
 };
 
 }  // namespace installer
 
 #endif  // CHROME_INSTALLER_UTIL_PRODUCT_OPERATIONS_H_