Add cloud datastore implementation.

impl/cloud/context.go

Index: impl/cloud/context.go
diff --git a/impl/cloud/context.go b/impl/cloud/context.go
new file mode 100644
index 0000000000000000000000000000000000000000..527f8e3d149fabf23a4616b61726e3381266288f
--- /dev/null
+++ b/impl/cloud/context.go
@@ -0,0 +1,26 @@
+// 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 cloud
+
+import (
+	"google.golang.org/cloud/datastore"
+
+	"golang.org/x/net/context"
+)
+
+// Use installs the cloud services implementation into the supplied Context.
+//
+// This includes:
+//	- github.com/luci/gae/service/info
+//	- github.com/luci/gae/service/datastore
+//
+// This is built around the ability to use cloud datastore.
+func Use(c context.Context, client *datastore.Client) context.Context {
+	cds := cloudDatastore{
+		client: client,
+	}
+
+	return cds.use(useInfo(c))
+}