Ensure peek-performance_bar doesn't break existing functionalities

Signed-off-by: Rémy Coutable <remy@rymai.me>

app/views/peek/views/_mysql2.html.haml

+%strong
+  %a#peek-show-queries{ href: '#' }
+    %span{ data: { defer_to: "#{view.defer_key}-duration" } }...
+    \/
+    %span{ data: { defer_to: "#{view.defer_key}-calls" } }...
+#modal-peek-pg-queries.modal{ tabindex: -1 }
+  .modal-dialog
+    #modal-peek-pg-queries-content.modal-content
+      .modal-header
+        %a.close{ href: "#", "data-dismiss" => "modal" } ×
+        %h4
+          SQL queries
+      .modal-body{ data: { defer_to: "#{view.defer_key}-queries" } }...
+mysql

config/initializers/peek.rb

@@ -26,3 +26,7 @@ class PEEK_DB_CLIENT
 end
 
 PEEK_DB_VIEW.prepend ::Gitlab::PerformanceBar::PeekQueryTracker
+
+class Peek::Views::PerformanceBar::ProcessUtilization
+  prepend ::Gitlab::PerformanceBar::PeekPerformanceBarWithRackBody
+end

lib/gitlab/performance_bar/peek_performance_bar_with_rack_body.rb

+# This solves a bug with a X-Senfile header that wouldn't be set properly, see
+# https://github.com/peek/peek-performance_bar/pull/27
+module Gitlab
+  module PerformanceBar
+    module PeekPerformanceBarWithRackBody
+      def call(env)
+        @env = env
+        reset_stats
+
+        @total_requests += 1
+        first_request if @total_requests == 1
+
+        env['process.request_start'] = @start.to_f
+        env['process.total_requests'] = total_requests
+
+        status, headers, body = @app.call(env)
+        body = Rack::BodyProxy.new(body) { record_request }
+        [status, headers, body]
+      end
+    end
+  end
+end