MD WebUI: Simplify usage of Templatizer in cr-lazy-render

ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js

Index: ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js
diff --git a/ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js b/ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js
index 0c4fb80e935048c9ad1682e0c448c2e9d5f6179e..99da50e48340df4781abe7f0d749b1103ca0069f 100644
--- a/ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js
+++ b/ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js
@@ -16,30 +16,6 @@
  *   });
  */
 
-/**
- * A template instance created by Polymer.Templatizer.
- * @constructor
- * @extends {PolymerElement}
- */
-var TemplateInstance = function() {};
-
-/** @type {Array<Element>} */
-TemplateInstance.prototype._children;
-
-/**
- * @param {string} prop
- * @param {Object} value
- * @param {boolean} quiet
- */
-TemplateInstance.prototype.__setProperty = function(prop, value, quiet) {};
-
-/**
- * @param {string} path
- * @param {Object} value
- * @param {boolean} quiet
- */
-TemplateInstance.prototype._notifyPath = function(path, value, quiet) {};
-
 Polymer({
   is: 'cr-lazy-render',
   extends: 'template',
@@ -51,8 +27,8 @@ Polymer({
   /** @private {Promise<Element>} */
   _renderPromise: null,
 
-  /** @private {TemplateInstance} */
-  _instance: null,
+  /** @private {TemplatizerNode} */
+  _child: null,

[Dan Beam, 2016/09/15 17:19:00]

use trailing underscore for Chrome JS unless it has to @override something, i.e.

renderPromise_
child_

[tsergeant, 2016/09/15 23:26:49]

I was originally trying to avoid things like `instance_._children` which was
confusing to write and read.

This CL cleans up several of those cases, so I've made the switch back to
trailing underscores.

 
   /**
    * Stamp the template into the DOM tree asynchronously
@@ -77,25 +53,18 @@ Polymer({
    *   already been stamped.
    */
   getIfExists: function() {
-    if (this._instance) {
-      var children = this._instance._children;
-
-      for (var i = 0; i < children.length; i++) {
-        if (children[i].nodeType == Node.ELEMENT_NODE)
-          return children[i];
-      }
-    }
-    return null;
+    return this._child;
   },
 
+  /** @private */

[Dan Beam, 2016/09/15 17:19:00]

is this actually private or @protected in polymer terminology?

[tsergeant, 2016/09/15 23:26:49]

It's private, yeah. Nothing else should be using it.

   _render: function() {
     if (!this.ctor)
       this.templatize(this);
     var parentNode = this.parentNode;
-    if (parentNode && !this._instance) {
-      this._instance = /** @type {TemplateInstance} */(this.stamp({}));
-      var root = this._instance.root;
-      parentNode.insertBefore(root, this);
+    if (parentNode && !this._child) {
+      var instance = this.stamp({});
+      this._child = instance.root.querySelector('*');

[michaelpg, 2016/09/15 08:44:41]

instance.root.firstElementChild

[tsergeant, 2016/09/15 23:26:49]

Done.

+      parentNode.insertBefore(instance.root, this);
     }
   },
 
@@ -104,8 +73,8 @@ Polymer({
    * @param {Object} value
    */
   _forwardParentProp: function(prop, value) {
-    if (this._instance)
-      this._instance.__setProperty(prop, value, true);
+    if (this._child)
+      this._child._templateInstance[prop] = value;
   },
 
   /**
@@ -113,7 +82,7 @@ Polymer({
    * @param {Object} value
    */
   _forwardParentPath: function(path, value) {
-    if (this._instance)
-      this._instance._notifyPath(path, value, true);
+    if (this._child)
+      this._child._templateInstance.notifyPath(path, value, true);
   }
 });