Remove some obsolete prefs.

components/content_settings/core/browser/content_settings_default_provider.h

Index: components/content_settings/core/browser/content_settings_default_provider.h
diff --git a/components/content_settings/core/browser/content_settings_default_provider.h b/components/content_settings/core/browser/content_settings_default_provider.h
index 5691a188ce4feb718bb5f3d33c55c297189283f9..f4f234695cac0af7bac48c25d3767bf216419226 100644
--- a/components/content_settings/core/browser/content_settings_default_provider.h
+++ b/components/content_settings/core/browser/content_settings_default_provider.h
@@ -72,16 +72,13 @@ class DefaultProvider : public ObservableProvider {
   // Called on prefs change.
   void OnPreferenceChanged(const std::string& pref_name);
 
-  // Clean up the obsolete preferences from the user's profile.
-  void DiscardObsoletePreferences();
-
   // Copies of the pref data, so that we can read it on the IO thread.
   std::map<ContentSettingsType, std::unique_ptr<base::Value>> default_settings_;
 
   PrefService* prefs_;
 
   // Whether this settings map is for an Incognito session.
-  bool is_incognito_;
+  const bool is_incognito_;
 
   // Used around accesses to the |default_settings_| object to guarantee
   // thread safety.