Add support for Pull Queues to prod implementation.

service/taskqueue/raw_interface.go

Index: service/taskqueue/raw_interface.go
diff --git a/service/taskqueue/raw_interface.go b/service/taskqueue/raw_interface.go
index 14aa920dce35ed1ff32b74426a759a7e61031c15..c4fe81a36c298ce1606e0cf45ea5bae9bf67f15e 100644
--- a/service/taskqueue/raw_interface.go
+++ b/service/taskqueue/raw_interface.go
@@ -4,6 +4,8 @@
 
 package taskqueue
 
+import "time"
+
 // RawCB is a simple callback for RawInterface.DeleteMulti, getting the error
 // for the attempted deletion.
 type RawCB func(error)
@@ -26,6 +28,10 @@ type RawInterface interface {
 	AddMulti(tasks []*Task, queueName string, cb RawTaskCB) error
 	DeleteMulti(tasks []*Task, queueName string, cb RawCB) error
 
+	Lease(maxTasks int, queueName string, leaseTime time.Duration) ([]*Task, error)
+	LeaseByTag(maxTasks int, queueName string, leaseTime time.Duration, tag string) ([]*Task, error)
+	ModifyLease(task *Task, queueName string, leaseTime time.Duration) error
+
 	Purge(queueName string) error
 
 	Stats(queueNames []string, cb RawStatsCB) error