App Banner Support for Android Chrome (#4103)

* App Banner Support for Android Chrome

* Oops, forgot semicolon;

app/assets/javascripts/discourse/initializers/android-app-banner-service-worker.js.es6

@@ -0,0 +1,16 @@
+// Android Chrome App Banner requires at least **one** service worker to be instantiate and https.
+// After Discourse starts to use service workers for other stuff (like mobile notification, offline mode, or ember)
+// we can ditch this.
+
+export default {
+  name: 'android-app-banner-service-worker',
+
+  initialize(container) {
+    const caps = container.lookup('capabilities:main');
+    const isSecure = document.location.protocol === 'https:';
+
+    if (isSecure && caps.isAndroid && 'serviceWorker' in navigator) {
+        navigator.serviceWorker.register(Discourse.BaseUri + '/service-worker.js', {scope: './'});
+    }
+  }
+};

app/controllers/metadata_controller.rb

@@ -4,12 +4,20 @@ class MetadataController < ApplicationController
 
   def manifest
     manifest = {
+      name: SiteSetting.title,
       short_name: SiteSetting.title,
       display: 'standalone',
       orientation: 'portrait',
       start_url: "#{Discourse.base_uri}/",
       background_color: "##{ColorScheme.hex_for_name('secondary')}",
-      theme_color: "##{ColorScheme.hex_for_name('header_background')}"
+      theme_color: "##{ColorScheme.hex_for_name('header_background')}",
+      icons: [
+        {
+          src: SiteSetting.apple_touch_icon_url,
+          sizes: "144x144",
+          type: "image/png"
+        }
+      ]
     }
 
     render json: manifest.to_json

public/service-worker.js

@@ -0,0 +1,4 @@
+/*
+ This service worker doesn't actually do anything!
+ I'm here just to support Google Chrome App Banner on Android
+ */