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

chrome/browser/content_settings/tab_specific_content_settings.cc

 // 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.
 
 #include "chrome/browser/content_settings/tab_specific_content_settings.h"
 
 #include <list>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 691 matching lines @@
     OnContentAllowed(CONTENT_SETTINGS_TYPE_PPAPI_BROKER);
   } else {
     OnContentBlocked(CONTENT_SETTINGS_TYPE_PPAPI_BROKER);
   }
 }
 
 void TabSpecificContentSettings::OnContentSettingChanged(
     const ContentSettingsPattern& primary_pattern,
     const ContentSettingsPattern& secondary_pattern,
     ContentSettingsType content_type,
+    ContentSetting previous_value,
     std::string resource_identifier) {
   const ContentSettingsDetails details(
       primary_pattern, secondary_pattern, content_type, resource_identifier);
   const NavigationController& controller = web_contents()->GetController();
   NavigationEntry* entry = controller.GetVisibleEntry();
   GURL entry_url;
   if (entry)
     entry_url = entry->GetURL();
   if (details.update_all() ||
       // The visible NavigationEntry is the URL in the URL field of a tab.
@@ skipping 134 matching lines @@
       static_cast<MicrophoneCameraStateFlags>(
           TabSpecificContentSettings::MICROPHONE_ACCESSED |
           TabSpecificContentSettings::MICROPHONE_BLOCKED |
           TabSpecificContentSettings::CAMERA_ACCESSED |
           TabSpecificContentSettings::CAMERA_BLOCKED);
   OnMediaStreamPermissionSet(
       web_contents()->GetLastCommittedURL(),
       media_blocked,
       std::string(), std::string(), std::string(), std::string());
 }