impl/prod: Make AEContext private.

impl/prod/module.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 prod
 
 import (
         "github.com/luci/gae/service/module"
         "golang.org/x/net/context"
         aeModule "google.golang.org/appengine/module"
 )
 
 // useModule adds a Module implementation to context.
 func useModule(usrCtx context.Context) context.Context {
         return module.SetFactory(usrCtx, func(ci context.Context) module.RawInterface {
-                return modImpl{AEContext(ci)}
+                return modImpl{getAEContext(ci)}
         })
 }
 
 type modImpl struct {
         aeCtx context.Context
 }
 
 func (m modImpl) List() ([]string, error) {
         return aeModule.List(m.aeCtx)
 }
@@ skipping 14 matching lines @@
         return aeModule.DefaultVersion(m.aeCtx, module)
 }
 
 func (m modImpl) Start(module, version string) error {
         return aeModule.Start(m.aeCtx, module, version)
 }
 
 func (m modImpl) Stop(module, version string) error {
         return aeModule.Stop(m.aeCtx, module, version)
 }