Milo Refactor: Remove theme support

milo/appengine/common/error.go

Index: milo/appengine/common/error.go
diff --git a/milo/appengine/common/error.go b/milo/appengine/common/error.go
new file mode 100644
index 0000000000000000000000000000000000000000..037e2b1d5cef82fbb31b008fd868566b845d2180
--- /dev/null
+++ b/milo/appengine/common/error.go
@@ -0,0 +1,20 @@
+// 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,
+	})
+}