[MD Extensions] Move search field out of downloads, use it in extensions

chrome/browser/resources/md_extensions/toolbar.js

+// Copyright 2015 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.
+
+cr.define('extensions', function() {
+  var Toolbar = Polymer({
+    is: 'extensions-toolbar',
+
+    /** @param {string} searchTerm */
+    onSearchTermSearch: function(searchTerm) {
+    },
+  });
+
+  /**
+   * @constructor
+   * @implements {SearchFieldDelegate}
+   */
+  // TODO(devlin): This is a bit excessive, and it would be better to just have
+  // Toolbar implement SearchFieldDelegate. But for now, we don't know how to
+  // make that happen with closure compiler.
+  function ToolbarSearchFieldDelegate(toolbar) {
+    this.toolbar_ = toolbar;
+  }
+
+  ToolbarSearchFieldDelegate.prototype = {
+    /** @override */
+    onSearchTermSearch: function(searchTerm) {
+      this.toolbar_.onSearchTermSearch(searchTerm);
+    }
+  };
+
+  return {Toolbar: Toolbar};
+});