Move webNavigation extension api into a separate directory

chrome/browser/extensions/api/web_navigation/web_navigation_api_constants.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
 // Constants used for the WebNavigation API.
 
-#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBNAVIGATION_API_CONSTANTS_H_
-#define CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBNAVIGATION_API_CONSTANTS_H_
+#ifndef CHROME_BROWSER_EXTENSIONS_API_WEB_NAVIGATION_WEB_NAVIGATION_API_CONSTANTS_H_
+#define CHROME_BROWSER_EXTENSIONS_API_WEB_NAVIGATION_WEB_NAVIGATION_API_CONSTANTS_H_
 #pragma once
 
-namespace extension_webnavigation_api_constants {
+namespace extensions {
+
+namespace web_navigation_api_constants {
 
 // Keys.
 extern const char kErrorKey[];
 extern const char kErrorOccurredKey[];
 extern const char kFrameIdKey[];
 extern const char kSourceTabIdKey[];
 extern const char kSourceFrameIdKey[];
 extern const char kTabIdKey[];
 extern const char kTimeStampKey[];
 extern const char kTransitionTypeKey[];
 extern const char kTransitionQualifiersKey[];
 extern const char kUrlKey[];
 
 // Events.
 extern const char kOnBeforeNavigate[];
 extern const char kOnCommitted[];
 extern const char kOnCompleted[];
 extern const char kOnCreatedNavigationTarget[];
 extern const char kOnDOMContentLoaded[];
 extern const char kOnErrorOccurred[];
 extern const char kOnReferenceFragmentUpdated[];
 
-}  // namespace extension_webnavigation_api_constants
+}  // namespace web_navigation_api_constants
 
-#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBNAVIGATION_API_CONSTANTS_H_
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_WEB_NAVIGATION_WEB_NAVIGATION_API_CONSTANTS_H_