[milo] {buildbucket,buildbot,swarming,logdog} -> backends/*.

milo/appengine/job_source/buildbot/master.go

 // Copyright 2016 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 buildbot
 
 import (
         "bytes"
         "compress/gzip"
         "encoding/json"
@@ skipping 131 matching lines @@
                 for _, bn := range sb {
                         // Go templates escapes this for us, and also
                         // slashes are not allowed in builder names.
                         ml.Builders = append(ml.Builders, *resp.NewLink(
                                 bn, fmt.Sprintf("/buildbot/%s/%s", entry.Name, bn)))
                 }
                 result.BuilderGroups = append(result.BuilderGroups, ml)
         }
         return result, nil
 }