Move extensions storage API implementation to src/extensions

extensions/browser/api/storage/settings_observer.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_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_OBSERVER_H_
-#define CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_OBSERVER_H_
+#ifndef EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_OBSERVER_H_
+#define EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_OBSERVER_H_
 
 #include "base/observer_list_threadsafe.h"
 #include "extensions/browser/api/storage/settings_namespace.h"
 
 namespace extensions {
 
 // Interface for classes that listen to changes to extension settings.
 class SettingsObserver {
  public:
   // Called when a list of settings have changed for an extension.
   virtual void OnSettingsChanged(
       const std::string& extension_id,
       settings_namespace::Namespace settings_namespace,
       const std::string& changes_json) = 0;
 
   virtual ~SettingsObserver() {}
 };
 
 typedef ObserverListThreadSafe<SettingsObserver>
     SettingsObserverList;
 
 }  // namespace extensions
 
-#endif  // CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_OBSERVER_H_
+#endif  // EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_OBSERVER_H_