Enforce the 'requirements' field in manifests.

chrome/common/extensions/extension.h

 // Copyright (c) 2012 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 CHROME_COMMON_EXTENSIONS_EXTENSION_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_H_
 
 #include <algorithm>
 #include <iosfwd>
 #include <map>
@@ skipping 83 matching lines @@
     EXTERNAL_EXTENSION_UNINSTALLED,
     NUM_STATES
   };
 
   // Used to record the reason an extension was disabled.
   enum DisableReason {
     DISABLE_UNKNOWN,
     DISABLE_USER_ACTION,
     DISABLE_PERMISSIONS_INCREASE,
     DISABLE_RELOAD,
+    DISABLE_UNSUPPORTED_REQUIREMENT,
     DISABLE_LAST,  // Not used.
   };
 
   enum InstallType {
     INSTALL_ERROR,
     DOWNGRADE,
     REINSTALL,
     UPGRADE,
     NEW_INSTALL
   };
@@ skipping 1063 matching lines @@
   // only the permissions that have added, and for Reason::REMOVED, this would
   // only contain the removed permissions.
   const PermissionSet* permissions;
 
   UpdatedExtensionPermissionsInfo(
       const Extension* extension,
       const PermissionSet* permissions,
       Reason reason);
 };
 
-} // namespace extensions
+}  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_H_