Extensions: remove DeprecatedDisableReason

extensions/browser/extension_prefs.h

Index: extensions/browser/extension_prefs.h
diff --git a/extensions/browser/extension_prefs.h b/extensions/browser/extension_prefs.h
index f86b02e939feca7a32f916ae3aa865418c2be5f6..13bff1e3d4098b38c90716f01d0f9f640bf77f77 100644
--- a/extensions/browser/extension_prefs.h
+++ b/extensions/browser/extension_prefs.h
@@ -633,9 +633,6 @@ class ExtensionPrefs : public ExtensionScopedPrefs, public KeyedService {
   // Migrates the permissions data in the pref store.
   void MigratePermissions(const ExtensionIdList& extension_ids);
 
-  // Migrates the disable reasons from a single enum to a bit mask.
-  void MigrateDisableReasons(const ExtensionIdList& extension_ids);
-
   // Checks whether there is a state pref for the extension and if so, whether
   // it matches |check_state|.
   bool DoesExtensionHaveState(const std::string& id,