Add UseBackground.

impl/prod/context.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package prod
 
 import (
         "fmt"
         "net/http"
         "net/http/cookiejar"
@@ skipping 68 matching lines @@
 //   - github.com/luci/gae/service/urlfetch
 //   - github.com/luci/gae/service/user
 //
 // These can be retrieved with the <service>.Get functions.
 //
 // The implementations are all backed by the real appengine SDK functionality,
 func Use(c context.Context, r *http.Request) context.Context {
         return setupAECtx(c, appengine.NewContext(r))
 }
 
+// UseBackground is the same as Use except that it activates production
+// implementations which aren't associated with any particular request.

[Vadim Sh., 2016/01/25 18:56:17]

What are conditions of it working? Can you please document them (i.e. MVM or
backgroud thread).

+func UseBackground(c context.Context) context.Context {
+        return setupAECtx(c, appengine.BackgroundContext())
+}
+
 // UseRemote is the same as Use, except that it lets you attach a context to
 // a remote host using the Remote API feature. See the docs for the
 // prerequisites.
 //
 // docs: https://cloud.google.com/appengine/docs/go/tools/remoteapi
 //
 // inOutCtx will be replaced with the new, derived context, if err is nil,
 // otherwise it's unchanged and continues to be safe-to-use.
 //
 // If client is nil, this will use create a new client, and will try to be
@@ skipping 51 matching lines @@
                 }
         }
 
         aeCtx, err := remote_api.NewRemoteContext(host, client)
         if err != nil {
                 return
         }
         *inOutCtx = setupAECtx(*inOutCtx, aeCtx)
         return nil
 }