Roll Polymer elements

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

Index: third_party/polymer/v1_0/components-chromium/app-layout/app-scroll-effects/effects/blend-background-extracted.js
diff --git a/third_party/polymer/v1_0/components-chromium/app-layout/app-scroll-effects/effects/blend-background-extracted.js b/third_party/polymer/v1_0/components-chromium/app-layout/app-scroll-effects/effects/blend-background-extracted.js
new file mode 100644
index 0000000000000000000000000000000000000000..e48b32a7095d74a2beb47227858fb09faf3c5953
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+++ b/third_party/polymer/v1_0/components-chromium/app-layout/app-scroll-effects/effects/blend-background-extracted.js
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+/**
+   * While scrolling down, fade in the rear background layer and fade out the front background
+   * layer (opacity interpolated based on scroll position).
+   */
+  Polymer.AppLayout.registerEffect('blend-background', {
+    /** @this Polymer.AppLayout.ElementWithBackground */
+    setUp: function setUp() {
+      this.$.backgroundFrontLayer.style.willChange = 'opacity';
+      this.$.backgroundFrontLayer.style.webkitTransform = 'translateZ(0)';
+      this.$.backgroundRearLayer.style.willChange = 'opacity';
+      this.$.backgroundRearLayer.style.webkitTransform = 'translateZ(0)';
+      this.$.backgroundRearLayer.style.opacity = 0;
+    },
+    /** @this Polymer.AppLayout.ElementWithBackground */
+    run: function run(p, y) {
+      this.$.backgroundFrontLayer.style.opacity = 1 - p;
+      this.$.backgroundRearLayer.style.opacity = p;
+    }
+  });