[milo] Refactor all html knowledge out of backends.

milo/frontend/view_logs.go

+// Copyright 2017 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 frontend
+
+import (
+        "github.com/luci/luci-go/milo/buildsource"
+        "github.com/luci/luci-go/server/router"
+        "github.com/luci/luci-go/server/templates"
+)
+
+// LogHandler is responsible for taking a universal build ID and rendering the
+// build page (defined in ./appengine/templates/pages/log.html).
+func LogHandler(c *router.Context, buildID buildsource.ID, logname string) {
+        log, closed, err := buildID.GetLog(c.Context, logname)
+        if err != nil {
+                ErrorHandler(c, err)
+        } else {
+                templates.MustRender(c.Context, c.Writer, "pages/log.html", templates.Args{
+                        "Log":    log,
+                        "Closed": closed,
+                })
+        }
+}