Compile print_preview, part 6: reduce down to 48 errors

chrome/browser/resources/print_preview/settings/page_settings.js

 // 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.
 
 cr.define('print_preview', function() {
   'use strict';
 
   /**
    * Creates a PageSettings object. This object encapsulates all settings and
    * logic related to page selection.
@@ skipping 83 matching lines @@
     /** @override */
     set isEnabled(isEnabled) {
       this.customInput_.disabled = !isEnabled;
       this.allRadio_.disabled = !isEnabled;
       this.customRadio_.disabled = !isEnabled;
     },
 
     /** @override */
     enterDocument: function() {
       print_preview.SettingsSection.prototype.enterDocument.call(this);
-      this.tracker.add(
-          this.allRadio_, 'click', this.onAllRadioClick_.bind(this));
-      this.tracker.add(
-          this.customRadio_, 'click', this.onCustomRadioClick_.bind(this));
-      this.tracker.add(
-          this.customInput_, 'blur', this.onCustomInputBlur_.bind(this));
-      this.tracker.add(
-          this.customInput_, 'focus', this.onCustomInputFocus_.bind(this));
-      this.tracker.add(
-          this.customInput_, 'keydown', this.onCustomInputKeyDown_.bind(this));
-      this.tracker.add(
-          this.customInput_, 'keyup', this.onCustomInputKeyUp_.bind(this));
-      this.tracker.add(
-          this.pageRangeTicketItem_,
+      this.tracker.add(assert(this.allRadio_), 'click',
+                       this.onAllRadioClick_.bind(this));
+      this.tracker.add(assert(this.customRadio_), 'click',
+                       this.onCustomRadioClick_.bind(this));
+      this.tracker.add(assert(this.customInput_), 'blur',
+                       this.onCustomInputBlur_.bind(this));
+      this.tracker.add(assert(this.customInput_), 'focus',
+                       this.onCustomInputFocus_.bind(this));
+      this.tracker.add(assert(this.customInput_), 'keydown',
+                       this.onCustomInputKeyDown_.bind(this));
+      this.tracker.add(assert(this.customInput_), 'keyup',
+                       this.onCustomInputKeyUp_.bind(this));
+      this.tracker.add(assert(this.pageRangeTicketItem_),
           print_preview.ticket_items.TicketItem.EventType.CHANGE,
           this.onPageRangeTicketItemChange_.bind(this));
     },
 
     /** @override */
     exitDocument: function() {
       print_preview.SettingsSection.prototype.exitDocument.call(this);
       this.customInput_ = null;
       this.customRadio_ = null;
       this.allRadio_ = null;
@@ skipping 131 matching lines @@
       }
       this.updateUiStateInternal();
     }
   };
 
   // Export
   return {
     PageSettings: PageSettings
   };
 });