Allow the user to "repair" a corrupted extension.

extensions/browser/uninstall_reason.h

 // Copyright 2014 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.
 
 #ifndef EXTENSIONS_BROWSER_UNINSTALL_REASON_H_
 #define EXTENSIONS_BROWSER_UNINSTALL_REASON_H_
 
 namespace extensions {
 
 enum UninstallReason {
   UNINSTALL_REASON_FOR_TESTING,         // Used for testing code only
   UNINSTALL_REASON_USER_INITIATED,      // User performed some UI gesture
   UNINSTALL_REASON_EXTENSION_DISABLED,  // Extension disabled due to error
   UNINSTALL_REASON_STORAGE_THRESHOLD_EXCEEDED,
   UNINSTALL_REASON_INSTALL_CANCELED,
   UNINSTALL_REASON_MANAGEMENT_API,
   UNINSTALL_REASON_SYNC,
   UNINSTALL_REASON_ORPHANED_THEME,
   UNINSTALL_REASON_ORPHANED_EPHEMERAL_EXTENSION,
   // The entries below imply bypassing checking user has permission to
   // uninstall the corresponding extension id.
   UNINSTALL_REASON_ORPHANED_EXTERNAL_EXTENSION,
   UNINSTALL_REASON_ORPHANED_SHARED_MODULE,
-  UNINSTALL_REASON_INTERNAL_MANAGEMENT  // Internal extensions (see usages)
+  UNINSTALL_REASON_INTERNAL_MANAGEMENT,  // Internal extensions (see usages)
+  UNINSTALL_REASON_REINSTALL
 };
 
 }  // extensions
 
 #endif  // EXTENSIONS_BROWSER_UNINSTALL_REASON_H_