Use native Pub/Sub library primitives.

common/gcloud/pubsub/quota.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 pubsub
 
 import (
-        "time"
+        "google.golang.org/cloud/pubsub"
 )
 
 // Cloud PubSub quota is documented here:
 // https://cloud.google.com/pubsub/quotas
 const (
         // MaxPublishSize is the maximum size, in bytes, of the published message
         // (10 MB).
         //
         // See: https://cloud.google.com/pubsub/publisher
         MaxPublishSize = 10 * 1024 * 1024
 
         // MaxPublishBatchSize is the maximum PubSub batch size.
-        MaxPublishBatchSize = 1000
+        MaxPublishBatchSize = pubsub.MaxPublishBatchSize
 
         // MaxProjectMessagesPerSecond is the maximum number of requests per second,
         // across the entire project.
         MaxProjectMessagesPerSecond = 10000
 
         // MaxSubscriptionPullSize is the maximum number of subscription records that
         // can be pulled at a time.
-        MaxSubscriptionPullSize = 100
-
-        // MaxMessageAckPerRequest is the maximum number of messages one can
-        // acknowledge in a single "acknowledge" call.
-        //
-        // NOTE: This is not verified, and is inspired by "MaxSubscriptionPullSize".
-        MaxMessageAckPerRequest = 100
-
-        // DefaultMaxAckDelay is the default maximum ACK delay.
-        DefaultMaxAckDelay = (60 * time.Second)
+        MaxSubscriptionPullSize = pubsub.DefaultMaxPrefetch
 )