Make the rest of the services have a similar raw/user interface structure.

service/taskqueue/raw_interface.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 taskqueue
+
+// RawCB is a simple callback for RawInterface.DeleteMulti, getting the error
+// for the attempted deletion.
+type RawCB func(error)
+
+// RawTaskCB is the callback for RawInterface.AddMulti, getting the added task
+// and an error.
+type RawTaskCB func(*Task, error)
+
+// RawStatsCB is the callback for RawInterface.Stats. It takes the statistics
+// object, as well as an error (e.g. in case the queue doesn't exist).
+type RawStatsCB func(*Statistics, error)
+
+// RawInterface is the full interface to the Task Queue service.
+type RawInterface interface {
+        // AddMulti adds multiple tasks to the given queue, calling cb for each item.
+        //
+        // The task passed to the callback function will have all the default values
+        // filled in, and will have the Name field populated, if the input task was
+        // anonymous (e.g. the Name field was blank).
+        AddMulti(tasks []*Task, queueName string, cb RawTaskCB) error
+        DeleteMulti(tasks []*Task, queueName string, cb RawCB) error
+
+        Purge(queueName string) error
+
+        Stats(queueNames []string, cb RawStatsCB) error
+}