Fix Chrome linker errors in GN build.

extensions/common/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 
 # GYP version: extensions/extensions.gyp:extensions_common
 source_set("common") {
   sources = [
     "api/messaging/message.h",
@@ skipping 90 matching lines @@
     "manifest_handlers/externally_connectable.cc",
     "manifest_handlers/externally_connectable.h",
     "manifest_handlers/file_handler_info.cc",
     "manifest_handlers/file_handler_info.h",
     "manifest_handlers/icons_handler.cc",
     "manifest_handlers/icons_handler.h",
     "manifest_handlers/incognito_info.cc",
     "manifest_handlers/incognito_info.h",
     "manifest_handlers/kiosk_mode_info.cc",
     "manifest_handlers/kiosk_mode_info.h",
+    "manifest_handlers/launcher_page_info.cc",
+    "manifest_handlers/launcher_page_info.h",
     "manifest_handlers/offline_enabled_info.cc",
     "manifest_handlers/offline_enabled_info.h",
     "manifest_handlers/permissions_parser.cc",
     "manifest_handlers/permissions_parser.h",
     "manifest_handlers/requirements_info.cc",
     "manifest_handlers/requirements_info.h",
     "manifest_handlers/sandboxed_page_info.cc",
     "manifest_handlers/sandboxed_page_info.h",
     "manifest_handlers/shared_module_info.cc",
     "manifest_handlers/shared_module_info.h",
@@ skipping 122 matching lines @@
       "manifest_handlers/nacl_modules_handler.h",
     ]
   }
 
   if (is_win) {
     cflags = [
       "/wd4267", # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     ]
   }
 }