arc: Handle ARC events in MD Settings

chrome/browser/resources/settings/android_apps_page/android_apps_page.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
  * 'android-apps-page' is the settings page for enabling android apps.
  */
 
 Polymer({
@@ skipping 36 matching lines @@
   ready: function() {
     cr.addWebUIListener(
         'android-apps-info-update', this.androidAppsInfoUpdate_.bind(this));
     this.browserProxy_.requestAndroidAppsInfo();
   },
   /**
    * @param {AndroidAppsInfo} info
    * @private
    */
   androidAppsInfoUpdate_: function(info) {
+    if (!this.parentElement)

[khmel, 2017/05/10 21:48:13]

in test this causes multiple listener invocation and as result multiple
navigateToPreviousRoute (which is async)

[stevenjb, 2017/05/10 22:35:44]

This is weird, we should avoid it. The test to settings.getCurrentRoute() should
be sufficient?

If not, try adding an observer to androidAppsInfo in the subpage and moving the
test there?

In practice, we don't necessarily need this. Any UI action that would cause this
change could close the details page, and if playStoreEnabled changes to false
while the details page is shown, it's not the end of the world if it remains
open.

[khmel, 2017/05/11 00:10:30]

settings.navigateToPreviousRoute() is async (windows.back)
so settings.getCurrentRoute() == settings.Route.ANDROID_APPS_DETAILS) will be
true several times.

it's not the end of the world but the end of the ideal world :)
Frankly speaking that looks really weird. I can close ARC OptIn window. This
disables ARC but settings still show "Remove Android Apps"
We have to handle this case.

[stevenjb, 2017/05/11 16:58:14]

When would that ever happen in practice?

Again, the best solution is probably to put the logic in the sub page instead.

[khmel, 2017/05/11 17:32:22]

I described when this happens above. For example open details page. Disable ARC
not from settings, for example closing ARC OptIn window when it shows start
page, LSO page or error page. ARC is disabled not but details settings are
shown.

Moved it to subpage.

+      return;
+
     this.androidAppsInfo_ = info;
+    if (!this.androidAppsInfo_.playStoreEnabled &&
+        settings.getCurrentRoute() == settings.Route.ANDROID_APPS_DETAILS) {
+      settings.navigateToPreviousRoute();
+    }
   },
 
   /**
    * @param {Event} event
    * @private
    */
   onEnableTap_: function(event) {
     this.setPrefValue('arc.enabled', true);
     event.stopPropagation();
   },
 
   /** @private */
   onSubpageTap_: function() {
-    if (this.androidAppsInfo_.appReady)
+    if (this.androidAppsInfo_.playStoreEnabled)
       settings.navigateTo(settings.Route.ANDROID_APPS_DETAILS);
   },
 });