ChromeOS: Implement Update screen of material design OOBE.

chrome/browser/resources/chromeos/login/oobe_update.js

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Polymer element for displaying material design Update screen.
+ */
+
+Polymer({
+  is: 'oobe-update-md',
+
+  properties: {
+    /**
+     * Shows "Checking for update ..." section and hides "Updating..." section.
+     */
+    checkingForUpdate: {
+      type: Boolean,
+      value: true,
+    },
+
+    /**
+     * Progress bar percent.
+     */
+    progressValue: {
+      type: Number,
+      value: 0,
+    },
+
+    /**
+     * Message "3 minutes left".
+     */
+    estimatedTimeLeft: {
+      type: String,
+    },
+
+    /**
+     * Shows estimatedTimeLeft.
+     */
+    estimatedTimeLeftShown: {
+      type: Boolean,
+    },
+
+    /**
+     * Message "33 percent done".
+     */
+    progressMessage: {
+      type: String,
+    },
+
+    /**
+     * Shows progressMessage.
+     */
+    progressMessageShown: {
+      type: Boolean,
+    },
+
+    /**
+     * Message above the progress bar.
+     */
+    updateUpperLabel: {
+      type: String,
+    },
+
+    /**
+     * If update cancellation is allowed.
+     */
+    cancelAllowed: {
+      type: Boolean,
+      value: false,
+    },
+  },
+
+  /**
+   * This updates "Cancel Update" message.
+   */
+  setCancelHint: function(message) {
+    this.$.cancelHint1.textContent = message;

[michaelpg, 2016/10/05 21:51:42]

optional: Would be more "Polymeric" to have a "cancelUpdateHint" property.
Instead of setting textContent (and i18n-content), you could then use
[[cancelUpdateHint]] in the two hint <div>s.

To initialize a property to the "cancelUpdateHint" string:

    cancelUpdateHint: {
      type: String,
      value: function() {
        return loadTimeData.getString('cancelUpdateHint');
      },
    },

[Alexander Alekseev, 2016/10/05 22:06:24]

I decided not to go this way because it would require onBeforeShow and
updateLocalizedContent hooks. This "dev-only" method seems to be simpler and
less error-prone.

+    this.$.cancelHint2.textContent = message;
+  },
+});