Remove some obsolete prefs.

components/content_settings/core/browser/content_settings_pref_provider.h

Index: components/content_settings/core/browser/content_settings_pref_provider.h
diff --git a/components/content_settings/core/browser/content_settings_pref_provider.h b/components/content_settings/core/browser/content_settings_pref_provider.h
index fd7bb42635f2ce5960bb15caeb22d84075a757be..65be16d049f38c171ca9e1980c96bbf7c21ef02c 100644
--- a/components/content_settings/core/browser/content_settings_pref_provider.h
+++ b/components/content_settings/core/browser/content_settings_pref_provider.h
@@ -80,16 +80,13 @@ class PrefProvider : public ObservableProvider {
               ContentSettingsType content_type,
               const std::string& resource_identifier);
 
-  // Clean up the obsolete preferences from the user's profile.
-  void DiscardObsoletePreferences();
-
   // Weak; owned by the Profile and reset in ShutdownOnUIThread.
   PrefService* prefs_;
 
   // Can be set for testing.
   std::unique_ptr<base::Clock> clock_;
 
-  bool is_incognito_;
+  const bool is_incognito_;
 
   PrefChangeRegistrar pref_change_registrar_;