Make Chrome splash screen same color as web UI's background color (#5169)

app/controllers/manifests_controller.rb

@@ -1,11 +1,7 @@
 # frozen_string_literal: true
 
 class ManifestsController < ApplicationController
-  before_action :set_instance_presenter
-
-  def show; end
-
-  def set_instance_presenter
-    @instance_presenter = InstancePresenter.new
+  def show
+    render json: InstancePresenter.new, serializer: ManifestSerializer
   end
 end

app/serializers/manifest_serializer.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+class ManifestSerializer < ActiveModel::Serializer
+  include RoutingHelper
+  include ActionView::Helpers::TextHelper
+
+  attributes :name, :short_name, :description,
+             :icons, :theme_color, :background_color,
+             :display, :start_url, :scope
+
+  def name
+    object.site_title
+  end
+
+  def short_name
+    object.site_title
+  end
+
+  def description
+    strip_tags(object.site_description.presence || I18n.t('about.about_mastodon_html'))
+  end
+
+  def icons
+    [
+      {
+        src: '/android-chrome-192x192.png',
+        sizes: '192x192',
+        type: 'image/png',
+      },
+    ]
+  end
+
+  def theme_color
+    '#282c37'
+  end
+
+  def background_color
+    '#191b22'
+  end
+
+  def display
+    'standalone'
+  end
+
+  def start_url
+    '/web/timelines/home'
+  end
+
+  def scope
+    root_url
+  end
+end

app/views/manifests/show.json.rabl

@@ -1,11 +0,0 @@
-object false
-
-node(:name)             { Setting.site_title }
-node(:short_name)       { Setting.site_title }
-node(:description)      { strip_tags(Setting.site_description.presence || I18n.t('about.about_mastodon_html')) }
-node(:icons)            { [{ src: '/android-chrome-192x192.png', sizes: '192x192', type: 'image/png' }] }
-node(:theme_color)      { '#282c37' }
-node(:background_color) { '#d9e1e8' }
-node(:display)          { 'standalone' }
-node(:start_url)        { '/web/timelines/home' }
-node(:scope)            { root_url }

spec/controllers/manifests_controller_spec.rb

@@ -8,10 +8,6 @@ describe ManifestsController do
       get :show, format: :json
     end
 
-    it 'assigns @instance_presenter' do
-      expect(assigns(:instance_presenter)).to be_kind_of InstancePresenter
-    end
-
     it 'returns http success' do
       expect(response).to have_http_status(:success)
     end