FEATURE: Add web manifest for Chrome users.

app/controllers/manifest_json_controller.rb

@@ -0,0 +1,15 @@
+class ManifestJsonController < ApplicationController
+  layout false
+  skip_before_filter :preload_json, :check_xhr
+
+  def index
+    manifest = {
+      short_name: SiteSetting.title,
+      display: 'browser',
+      orientation: 'portrait',
+      start_url: "#{Discourse.base_uri}/"
+    }
+
+    render json: manifest.to_json
+  end
+end