Prevent focus from leaving Print Preview overlay controls.

chrome/browser/resources/print_preview/print_preview.js

Index: chrome/browser/resources/print_preview/print_preview.js
diff --git a/chrome/browser/resources/print_preview/print_preview.js b/chrome/browser/resources/print_preview/print_preview.js
index 9fe9806edb088bdb2f2c819482ff1cb475e081f6..cd8c4867335023351375bf422428c612f982642c 100644
--- a/chrome/browser/resources/print_preview/print_preview.js
+++ b/chrome/browser/resources/print_preview/print_preview.js
@@ -7,6 +7,7 @@
 var localStrings = new LocalStrings(templateData);
 
 <include src="component.js"/>
+<include src="print_preview_focus_manager.js"/>
 
 cr.define('print_preview', function() {
   'use strict';
@@ -255,6 +256,7 @@ cr.define('print_preview', function() {
         this.setIsEnabled_(false);
       }
       this.nativeLayer_.startGetInitialSettings();
+      print_preview.PrintPreviewFocusManager.getInstance().initialize();
       cr.ui.FocusOutlineManager.forDocument(document);
     },