Expand usage of platform-apps flag and permission features.

chrome/common/extensions/extension_manifest_constants.cc

 // 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.
 
 #include "chrome/common/extensions/extension_manifest_constants.h"
 
 namespace extension_manifest_keys {
 
 const char kAllFrames[] = "all_frames";
 const char kAltKey[] = "altKey";
@@ skipping 437 matching lines @@
 const char kMissingFile[] =
     "At least one js or css file is required for 'content_scripts[*]'.";
 const char kMultipleOverrides[] =
     "An extension cannot override more than one page.";
 const char kNoWildCardsInPaths[] =
   "Wildcards are not allowed in extent URL pattern paths.";
 const char kOneUISurfaceOnly[] =
     "Only one of 'browser_action', 'page_action', and 'app' can be specified.";
 const char kPermissionNotAllowed[] =
     "Access to permission '*' denied.";
+const char kPlatformAppFlagRequired[] =
+    "Loading platform_app extension type is turned off by default. "
+    "You can enable this type with the --enable-platform-apps "
+    "command-line flag.";
 const char kReservedMessageFound[] =
     "Reserved key * found in message catalog.";
 #if defined(OS_CHROMEOS)
 const char kIllegalPlugins[] =
     "Extensions cannot install plugins on Chrome OS";
 #endif
 }  // namespace extension_manifest_errors