plugins/pjax/views/layouts/pjax.html.erb
<%
update_js = render(file: "#{Rails.root}/public/designs/themes/#{current_theme}/pjax_update.js.erb").to_json rescue nil
%>
<title><%= h page_title %></title>
<%= render file: "#{Rails.root}/public/designs/themes/#{current_theme}/layouts/_content.html.erb" rescue
render "layouts/content" %>
<%= javascript_tag do %>
<%= render 'pjax_shared/load_state.js' %>
<% if update_js %>
state.theme_update_js = <%= update_js %>;
<% end %>
pjax.update(state);
<% end %>