Make the hcsm and its providers communicate via an observer interface.

chrome/browser/content_settings/content_settings_extension_provider.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_CONTENT_SETTINGS_CONTENT_SETTINGS_EXTENSION_PROVIDER_H_
 #define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_EXTENSION_PROVIDER_H_
 
 #include <string>
 
-#include "chrome/browser/content_settings/content_settings_provider.h"
+#include "chrome/browser/content_settings/content_settings_observable_provider.h"
 #include "chrome/browser/extensions/extension_content_settings_store.h"
 
 class ContentSettingsDetails;
 class HostContentSettingsMap;
 class Profile;
 
 namespace content_settings {
 
+class Observer;
+
 // A content settings provider which manages settings defined by extensions.
-class ExtensionProvider : public ProviderInterface,
+class ExtensionProvider : public ObservableProvider,
                           public ExtensionContentSettingsStore::Observer {
  public:
-  ExtensionProvider(HostContentSettingsMap* map,
-                    ExtensionContentSettingsStore* extensions_settings,
+  ExtensionProvider(ExtensionContentSettingsStore* extensions_settings,
                     bool incognito);
 
   virtual ~ExtensionProvider();
 
-  // ProviderInterface methods:
+  // Provider Interface implementations.
   virtual ContentSetting GetContentSetting(
       const GURL& embedded_url,
       const GURL& top_level_url,
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier) const;
 
   virtual void SetContentSetting(
       const ContentSettingsPattern& embedded_url_pattern,
       const ContentSettingsPattern& top_level_url_pattern,
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier,
       ContentSetting content_setting) {}
 
   virtual void GetAllContentSettingsRules(
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier,
       Rules* content_setting_rules) const;
 
   virtual void ClearAllContentSettingsRules(ContentSettingsType content_type) {}
 
   virtual void ResetToDefaults() {}
 
   virtual void ShutdownOnUIThread();
 
   // ExtensionContentSettingsStore::Observer methods:
   virtual void OnContentSettingChanged(const std::string& extension_id,
                                        bool incognito);
 
  private:
-  void NotifyObservers(const ContentSettingsDetails& details);
-
-  // The HostContentSettingsMap this provider belongs to. It is only
-  // used as the source for notifications.
-  // TODO(markusheintz): Make the HCSM an Observer of the
-  // ContentSettingsProvider and send out the Notifications itself.
-  HostContentSettingsMap* map_;
-
   // Specifies whether this provider manages settings for incognito or regular
   // sessions.
   bool incognito_;
 
   // The backend storing content setting rules defined by extensions.
   scoped_refptr<ExtensionContentSettingsStore> extensions_settings_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionProvider);
 };
 
 }  // namespace content_settings
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_EXTENSION_PROVIDER_H_