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

chrome/browser/content_settings/tab_specific_content_settings.cc

Index: chrome/browser/content_settings/tab_specific_content_settings.cc
diff --git a/chrome/browser/content_settings/tab_specific_content_settings.cc b/chrome/browser/content_settings/tab_specific_content_settings.cc
index 892f296be2559a90a8fad25d227ab8eb692dddbe..774902e205a2d94492e2429d2642e4c49c63d3f2 100644
--- a/chrome/browser/content_settings/tab_specific_content_settings.cc
+++ b/chrome/browser/content_settings/tab_specific_content_settings.cc
@@ -709,6 +709,7 @@ 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);