Compile print_preview, part 6: reduce down to 48 errors

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

Index: chrome/browser/resources/print_preview/settings/page_settings.js
diff --git a/chrome/browser/resources/print_preview/settings/page_settings.js b/chrome/browser/resources/print_preview/settings/page_settings.js
index f86c02dd5a1e50a102d9037d7dc7c6a64488e22d..9b2d6f22edbdcb8a526d2dba8a6d11a57b802c3f 100644
--- a/chrome/browser/resources/print_preview/settings/page_settings.js
+++ b/chrome/browser/resources/print_preview/settings/page_settings.js
@@ -101,20 +101,19 @@ cr.define('print_preview', function() {
     /** @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));
     },