Implement info.ServiceAccount() on devserver via info.AccessToken(...).

impl/prod/info.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 prod
 
 import (
         "time"
 
         "github.com/luci/gae/service/info"
@@ skipping 81 matching lines @@
         }
         return ret, nil
 }
 func (g giImpl) RequestID() string {
         return appengine.RequestID(g.aeCtx)
 }
 func (g giImpl) ServerSoftware() string {
         return appengine.ServerSoftware()
 }
 func (g giImpl) ServiceAccount() (string, error) {
+        if appengine.IsDevAppServer() {
+                // On devserver ServiceAccount returns empty string, but AccessToken works.
+                // We use it to grab developer's email.
+                return developerAccount(g.aeCtx)
+        }
         return appengine.ServiceAccount(g.aeCtx)
 }
 func (g giImpl) SignBytes(bytes []byte) (keyName string, signature []byte, err error) {
         return appengine.SignBytes(g.aeCtx, bytes)
 }
 func (g giImpl) VersionID() string {
         return appengine.VersionID(g.aeCtx)
 }
 
 func (g giImpl) Testable() info.Testable {
@@ skipping 20 matching lines @@
 func getProbeCache(c context.Context) *infoProbeCache {
         if pc, ok := c.Value(probeCacheKey).(*infoProbeCache); ok {
                 return pc
         }
         return nil
 }
 
 func withProbeCache(c context.Context, pc *infoProbeCache) context.Context {
         return context.WithValue(c, probeCacheKey, pc)
 }