Milo Refactor: Remove theme support

milo/appengine/common/error.go

+// Copyright 2015 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package common
+
+import (
+        "github.com/luci/luci-go/server/router"
+        "github.com/luci/luci-go/server/templates"
+)
+
+// ErrorPage writes an error page into c.Writer with an http code "code"
+// and custom message.
+func ErrorPage(c *router.Context, code int, message string) {
+        c.Writer.WriteHeader(code)
+        templates.MustRender(c.Context, c.Writer, "pages/error.html", templates.Args{
+                "Code":    code,
+                "Message": message,
+        })
+}