kiosk: Add kiosk.always_update manifest key

extensions/common/manifest_handlers/kiosk_mode_info.h

Index: extensions/common/manifest_handlers/kiosk_mode_info.h
diff --git a/extensions/common/manifest_handlers/kiosk_mode_info.h b/extensions/common/manifest_handlers/kiosk_mode_info.h
index bd37f969c65ba16279af4ce1339b6bea3eaead41..b7525bd62d5d5838981396c879824ec98dd6dc76 100644
--- a/extensions/common/manifest_handlers/kiosk_mode_info.h
+++ b/extensions/common/manifest_handlers/kiosk_mode_info.h
@@ -25,7 +25,8 @@ struct KioskModeInfo : public Extension::ManifestData {
 
   KioskModeInfo(KioskStatus kiosk_status,
                 const std::vector<std::string>& secondary_app_ids,
-                const std::string& required_platform_version);
+                const std::string& required_platform_version,
+                bool always_update);
   ~KioskModeInfo() override;
 
   // Gets the KioskModeInfo for |extension|, or NULL if none was
@@ -51,6 +52,7 @@ struct KioskModeInfo : public Extension::ManifestData {
   const std::vector<std::string> secondary_app_ids;
 
   const std::string required_platform_version;
+  const bool always_update;
 };
 
 // Parses the "kiosk_enabled" and "kiosk_only" manifest keys.