Compile search_box in gyp v2.

ui/file_manager/externs/search_item.js

Index: ui/file_manager/externs/search_item.js
diff --git a/ui/file_manager/externs/search_item.js b/ui/file_manager/externs/search_item.js
new file mode 100644
index 0000000000000000000000000000000000000000..f39f032848c52f2582849fc42200ba293e9557df
--- /dev/null
+++ b/ui/file_manager/externs/search_item.js
@@ -0,0 +1,18 @@
+// Copyright 2017 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.
+
+/**
+ * @constructor
+ */
+function SearchItem() {}
+
+/**
+ * @type {boolean}
+ */
+SearchItem.prototype.isHeaderItem;
+
+/**
+ * @type {string}
+ */
+SearchItem.prototype.searchQuery;