Compile print_preview, part 2: reduce down to 260 errors

chrome/browser/resources/print_preview/common/search_box.js

 // 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.
 
 cr.define('print_preview', function() {
   'use strict';
 
   /**
    * Component that renders a search box for searching through destinations.
    * @param {string} searchBoxPlaceholderText Search box placeholder text.
@@ skipping 33 matching lines @@
   /**
    * Delay in milliseconds before dispatching a SEARCH event.
    * @private {number}
    * @const
    */
   SearchBox.SEARCH_DELAY_ = 150;
 
   SearchBox.prototype = {
     __proto__: print_preview.Component.prototype,
 
-    /** @param {string} query New query to set the search box's query to. */
+    /** @param {?string} query New query to set the search box's query to. */
     setQuery: function(query) {
       query = query || '';
       this.input_.value = query.trim();
     },
 
     /** Sets the input element of the search box in focus. */
     focus: function() {
       this.input_.focus();
     },
 
     /** @override */
     createDom: function() {
       this.setElementInternal(this.cloneTemplateInternal(
           'search-box-template'));
       this.input_ = this.getChildElement('.search-box-input');
       this.input_.setAttribute('placeholder', this.searchBoxPlaceholderText_);
     },
 
     /** @override */
     enterDocument: function() {
       print_preview.Component.prototype.enterDocument.call(this);
-      this.tracker.add(this.input_, 'input', this.onInputInput_.bind(this));
+      this.tracker.add(assert(this.input_), 'input',
+                       this.onInputInput_.bind(this));
     },
 
     /** @override */
     exitDocument: function() {
       print_preview.Component.prototype.exitDocument.call(this);
       this.input_ = null;
     },
 
     /**
      * @return {string} The current query of the search box.
@@ skipping 32 matching lines @@
       this.timeout_ = setTimeout(
           this.dispatchSearchEvent_.bind(this), SearchBox.SEARCH_DELAY_);
     }
   };
 
   // Export
   return {
     SearchBox: SearchBox
   };
 });