Cleanup: IWYU for base/gtest_prod_util.h.

chrome/browser/extensions/api/content_settings/content_settings_api.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_BROWSER_EXTENSIONS_API_CONTENT_SETTINGS_CONTENT_SETTINGS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_CONTENT_SETTINGS_CONTENT_SETTINGS_API_H_
 
+#include "base/gtest_prod_util.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
 
 class PluginFinder;
 
 namespace content {
 struct WebPluginInfo;
 }
 
 namespace extensions {
 
@@ skipping 50 matching lines @@
                            ContentSettingsGetResourceIdentifiers);
 
   // Callback method that gets executed when |plugins|
   // are asynchronously fetched.
   void OnGotPlugins(const std::vector<content::WebPluginInfo>& plugins);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_CONTENT_SETTINGS_CONTENT_SETTINGS_API_H_