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

milo/appengine/job_source/buildbot/structs.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 419 matching lines @@
                         PendingBuilds   int    `json:"pending_builds"`
                         State           string `json:"state"`
                         TotalSlaves     int    `json:"total_slaves"`
                 } `json:"builders"`
                 ServerUptime float64 `json:"server_uptime"`
         } `json:"varz"`
 
         // This is injected by the pubsub publisher on the buildbot side.
         Name string `json:"name"`
 }