Add "MkKeyContext" KeyContext generation function.

impl/memory/datastore_query_execution_test.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 memory
 
 import (
         "fmt"
         "strings"
         "testing"
         "time"
 
         "github.com/luci/gae/service/blobstore"
         ds "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/info"
         "golang.org/x/net/context"
 
         . "github.com/luci/luci-go/common/testing/assertions"
         . "github.com/smartystreets/goconvey/convey"
 )
 
 func mkKey(appID, namespace string, elems ...interface{}) *ds.Key {
-        return ds.KeyContext{appID, namespace}.MakeKey(elems...)
+        return ds.MkKeyContext(appID, namespace).MakeKey(elems...)
 }
 
 type qExpect struct {
         q     *ds.Query
         inTxn bool
 
         get   []ds.PropertyMap
         keys  []*ds.Key
         count int
 }
@@ skipping 599 matching lines @@
 
         v, ok := actual.(error)
         if !ok {
                 return fmt.Sprintf("type of 'actual' must be error, not %T", actual)
         }
         if v == nil || v == ds.Stop {
                 return ""
         }
         return fmt.Sprintf("expected success value, not %v", v)
 }