[Do not commit] Track revocations in content_settings::Observer

chrome/browser/content_settings/tab_specific_content_settings.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_CONTENT_SETTINGS_TAB_SPECIFIC_CONTENT_SETTINGS_H_
 #define CHROME_BROWSER_CONTENT_SETTINGS_TAB_SPECIFIC_CONTENT_SETTINGS_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 373 matching lines @@
       const GURL& validated_url,
       bool is_error_page,
       bool is_iframe_srcdoc) override;
   void AppCacheAccessed(const GURL& manifest_url,
                         bool blocked_by_policy) override;
 
   // content_settings::Observer implementation.
   void OnContentSettingChanged(const ContentSettingsPattern& primary_pattern,
                                const ContentSettingsPattern& secondary_pattern,
                                ContentSettingsType content_type,
+                               ContentSetting previous_value,
                                std::string resource_identifier) override;
 
   // Notifies all registered |SiteDataObserver|s.
   void NotifySiteDataObservers();
 
   // Clears the Geolocation settings.
   void ClearGeolocationContentSettings();
 
   // Clears the MIDI settings.
   void ClearMidiContentSettings();
@@ skipping 63 matching lines @@
   std::string media_stream_requested_audio_device_;
   std::string media_stream_requested_video_device_;
 
   // Observer to watch for content settings changed.
   ScopedObserver<HostContentSettingsMap, content_settings::Observer> observer_;
 
   DISALLOW_COPY_AND_ASSIGN(TabSpecificContentSettings);
 };
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_TAB_SPECIFIC_CONTENT_SETTINGS_H_