Add meta tags for hiding referrer on private asciicast pages

app/serializers/asciicast_serializer.rb

@@ -4,4 +4,9 @@ class AsciicastSerializer < ActiveModel::Serializer
   attributes :id, :duration, :stdout_frames_url, :snapshot
   attribute :terminal_columns, key: :width
   attribute :terminal_lines, key: :height
+
+  def private?
+    object.private?
+  end
+
 end

app/views/asciicasts/_player.html.erb

@@ -1,3 +1,10 @@
+<% if asciicast.private? %>
+  <% content_for(:head) do %>
+    <meta name="robots" content="noindex, nofollow">
+    <meta name="referrer" content="none">
+  <% end %>
+<% end %>
+
 <div class="player"></div>
 
 <p class="processing-info" style="display: none">

app/views/layouts/bare.html.slim

@@ -6,5 +6,6 @@ html[lang="en"]
     title = page_title
     = stylesheet_link_tag 'embed', :media => 'all'
     = javascript_include_tag 'embed'
+    = content_for(:head)
   body.iframe
     = yield

app/views/layouts/screenshot.html.slim

@@ -4,5 +4,6 @@ html[lang="en"]
     meta[charset="utf-8"]
     = screenshot_javascript_tag
     = screenshot_stylesheet_tag
+    = content_for(:head)
   body.screenshot
     = yield