Quick view lazy load: initialize quick view element lazily.

ui/file_manager/file_manager/foreground/js/quick_view_controller.js

Index: ui/file_manager/file_manager/foreground/js/quick_view_controller.js
diff --git a/ui/file_manager/file_manager/foreground/js/quick_view_controller.js b/ui/file_manager/file_manager/foreground/js/quick_view_controller.js
index 764ed09f34548a8d5580da8a8cfe39e58a92e878..25667c77adc378c35d2996dc9c1bf19c282b5086 100644
--- a/ui/file_manager/file_manager/foreground/js/quick_view_controller.js
+++ b/ui/file_manager/file_manager/foreground/js/quick_view_controller.js
@@ -115,12 +115,18 @@ QuickViewController.prototype.init_ = function(quickView) {
 
 /**
  * Craete quick view element.
- * TODO(oka): lazy load quick view element for fast Files App initialization.
  * @return Promise<!FilesQuickView>
  * @private
  */
 QuickViewController.prototype.createQuickView_ = function() {
-  return Promise.resolve(document.querySelector('#quick-view'));
+  return new Promise(function(resolve, reject) {
+    Polymer.Base.importHref(
+        'foreground/elements/files_quick_view.html', function() {
+          var quickView = document.querySelector('#quick-view');
+          i18nTemplate.process(quickView, loadTimeData);
+          resolve(quickView);
+        }, reject);
+  });
 };
 
 /**