Roll Polymer elements

third_party/polymer/v1_0/components-chromium/app-layout/app-scroll-effects/effects/parallax-background-extracted.js

+/**
+   * Vertically translate the background based on a factor of the scroll position.
+   */
+  Polymer.AppLayout.registerEffect('parallax-background', {
+    /**
+     * @param {{scalar: string}} config
+     * @this Polymer.AppLayout.ElementWithBackground
+     */
+    setUp: function setUp(config) {
+      var scalar = parseFloat(config.scalar);
+
+      this._deltaBg = this.$.backgroundFrontLayer.offsetHeight - this.$.background.offsetHeight;
+      if (this._deltaBg === 0) {
+        if (isNaN(scalar)) {
+          scalar = 0.8;
+        }
+        this._deltaBg = this._dHeight * scalar;
+      } else {
+        if (isNaN(scalar)) {
+          scalar = 1;
+        }
+        this._deltaBg = this._deltaBg * scalar;
+      }
+    },
+    /** @this Polymer.AppLayout.ElementWithBackground */
+    tearDown: function tearDown() {
+      delete this._deltaBg;
+    },
+    /** @this Polymer.AppLayout.ElementWithBackground */
+    run: function run(p, y) {
+      this.transform('translate3d(0px, ' + (this._deltaBg * Math.min(1, p)) + 'px, 0px)', this.$.backgroundFrontLayer);
+      if (this.$.backgroundRearLayer) {
+        this.transform('translate3d(0px, ' + (this._deltaBg * Math.min(1, p)) + 'px, 0px)', this.$.backgroundRearLayer);
+      }
+    }
+  });