Add an update warning for downloading over mobile data

chrome/browser/resources/settings/about_page/about_page.js

Index: chrome/browser/resources/settings/about_page/about_page.js
diff --git a/chrome/browser/resources/settings/about_page/about_page.js b/chrome/browser/resources/settings/about_page/about_page.js
index 36f8b61d2081d3db66c908af6c3495637c691b40..1ad7867a559fa0e5f16daf0d8140e2b05e5e5774 100644
--- a/chrome/browser/resources/settings/about_page/about_page.js
+++ b/chrome/browser/resources/settings/about_page/about_page.js
@@ -1,7 +1,6 @@
 // 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 'settings-about-page' contains version and OS related
  * information.
@@ -84,7 +83,13 @@ Polymer({
             '#detailed-build-info-trigger');
         return map;
       },
-    }
+    },
+
+    /** @private */
+    showUpdateWarningDialog_: {
+      type: Boolean,
+      value: false,
+    },
 // </if>
   },
 
@@ -163,6 +168,21 @@ Polymer({
 // <if expr="chromeos">
     if (event.status == UpdateStatus.CHECKING)
       this.hasCheckedForUpdates_ = true;
+    else if (event.status == UpdateStatus.NEED_PERMISSION_TO_UPDATE) {
+      this.showUpdateWarningDialog_ = true;
+      // Async to wait for dialog to appear in the DOM.
+      this.async(function() {
+        var dialog = this.$$('settings-update-warning-dialog');
+        // event includes the update version and size in bytes.
+        dialog.setUpdateWarningMessage(event.version, event.size);
+        // Register listener to detect when the dialog is closed. Flip the
+        // boolean once closed to force a restamp next time it is shown such
+        // that the previous dialog's contents are cleared.
+        dialog.addEventListener('close', function() {
+          this.showUpdateWarningDialog_ = false;
+        }.bind(this));
+      }.bind(this));
+    }
 // </if>
     this.currentUpdateStatusEvent_ = event;
   },
@@ -258,6 +278,8 @@ Polymer({
     switch (this.currentUpdateStatusEvent_.status) {
       case UpdateStatus.CHECKING:
         return this.i18n('aboutUpgradeCheckStarted');
+      case UpdateStatus.NEED_PERMISSION_TO_UPDATE:
+        return "";
       case UpdateStatus.NEARLY_UPDATED:
 // <if expr="chromeos">
         if (this.currentChannel_ != this.targetChannel_)
@@ -399,7 +421,8 @@ Polymer({
     var staleUpdatedStatus = !this.hasCheckedForUpdates_ &&
         this.checkStatus_(UpdateStatus.UPDATED);
 
-    return staleUpdatedStatus || this.checkStatus_(UpdateStatus.FAILED);
+    return staleUpdatedStatus || this.checkStatus_(UpdateStatus.FAILED) ||
+        this.checkStatus_(UpdateStatus.NEED_PERMISSION_TO_UPDATE);
   },
 
   /**