Refactor a bit.

impl/prod/datastore_key.go

Index: impl/prod/datastore_key.go
diff --git a/prod/datastore_key.go b/impl/prod/datastore_key.go
similarity index 74%
rename from prod/datastore_key.go
rename to impl/prod/datastore_key.go
index 7dc76f974a23edb82fda150822ca2f57a47aee1b..ac1980a97644f289e8a31f9cbfb4301c7ff079ac 100644
--- a/prod/datastore_key.go
+++ b/impl/prod/datastore_key.go
@@ -5,8 +5,7 @@
 package prod
 
 import (
-	"github.com/luci/gae"
-	"github.com/luci/gae/helper"
+	rds "github.com/luci/gae/service/rawdatastore"
 	"google.golang.org/appengine/datastore"
 )
 
@@ -14,12 +13,12 @@ type dsKeyImpl struct {
 	*datastore.Key
 }
 
-var _ gae.DSKey = dsKeyImpl{}
+var _ rds.Key = dsKeyImpl{}
 
-func (k dsKeyImpl) Parent() gae.DSKey { return dsR2F(k.Key.Parent()) }
+func (k dsKeyImpl) Parent() rds.Key { return dsR2F(k.Key.Parent()) }
 
-// dsR2F (DS real-to-fake) converts an SDK Key to a gae.DSKey
-func dsR2F(k *datastore.Key) gae.DSKey {
+// dsR2F (DS real-to-fake) converts an SDK Key to a rds.Key
+func dsR2F(k *datastore.Key) rds.Key {
 	return dsKeyImpl{k}
 }
 
@@ -35,7 +34,7 @@ func dsR2F(k *datastore.Key) gae.DSKey {
 //     return nil, err
 //   }
 //   return dsR2F(k), nil
-func dsR2FErr(k *datastore.Key, err error) (gae.DSKey, error) {
+func dsR2FErr(k *datastore.Key, err error) (rds.Key, error) {
 	if err != nil {
 		return nil, err
 	}
@@ -43,13 +42,13 @@ func dsR2FErr(k *datastore.Key, err error) (gae.DSKey, error) {
 }
 
 // dsF2R (DS fake-to-real) converts a DSKey back to an SDK *Key.
-func dsF2R(k gae.DSKey) *datastore.Key {
+func dsF2R(k rds.Key) *datastore.Key {
 	if rkey, ok := k.(dsKeyImpl); ok {
 		return rkey.Key
 	}
 	// we should always hit the fast case above, but just in case, safely round
 	// trip through the proto encoding.
-	rkey, err := datastore.DecodeKey(helper.DSKeyEncode(k))
+	rkey, err := datastore.DecodeKey(rds.KeyEncode(k))
 	if err != nil {
 		// should never happen in a good program, but it's not ignorable, and
 		// passing an error back makes this function too cumbersome (and it causes
@@ -62,8 +61,8 @@ func dsF2R(k gae.DSKey) *datastore.Key {
 
 // dsMR2F (DS multi-real-to-fake) converts a slice of SDK keys to their wrapped
 // types.
-func dsMR2F(ks []*datastore.Key) []gae.DSKey {
-	ret := make([]gae.DSKey, len(ks))
+func dsMR2F(ks []*datastore.Key) []rds.Key {
+	ret := make([]rds.Key, len(ks))
 	for i, k := range ks {
 		ret[i] = dsR2F(k)
 	}
@@ -71,7 +70,7 @@ func dsMR2F(ks []*datastore.Key) []gae.DSKey {
 }
 
 // dsMF2R (DS multi-fake-to-fake) converts a slice of wrapped keys to SDK keys.
-func dsMF2R(ks []gae.DSKey) []*datastore.Key {
+func dsMF2R(ks []rds.Key) []*datastore.Key {
 	ret := make([]*datastore.Key, len(ks))
 	for i, k := range ks {
 		ret[i] = dsF2R(k)