[errors] de-specialize Transient in favor of Tags.

common/gcloud/gs/writer.go

 // Copyright 2015 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 gs
 
 import (
         "io"
         "time"
 
         gs "cloud.google.com/go/storage"
-        "github.com/luci/luci-go/common/errors"
         log "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/retry"
+        "github.com/luci/luci-go/common/retry/transient"
         "golang.org/x/net/context"
 )
 
 // Writer is an augmented io.WriteCloser instance.
 type Writer interface {
         io.WriteCloser
 
         // Count returns the number of bytes written by the object.
         Count() int64
 }
@@ skipping 10 matching lines @@
         relpath string
         count   int64
 }
 
 // Write writes data with exponenital backoff/retry.
 func (w *prodWriter) Write(d []byte) (a int, err error) {
         if w.Writer == nil {
                 w.Writer = w.client.baseClient.Bucket(w.bucket).Object(w.relpath).NewWriter(w)
         }
 
-        err = retry.Retry(w, retry.TransientOnly(retry.Default), func() (ierr error) {
+        err = retry.Retry(w, transient.Only(retry.Default), func() (ierr error) {
                 a, ierr = w.Writer.Write(d)
 
                 // Assume all Write errors are transient.
-                ierr = errors.WrapTransient(ierr)
+                ierr = transient.Tag.Apply(ierr)
                 return
         }, func(err error, d time.Duration) {
                 log.Fields{
                         log.ErrorKey: err,
                         "delay":      d,
                         "bucket":     w.bucket,
                         "path":       w.relpath,
                 }.Warningf(w, "Transient error on GS write. Retrying...")
         })
 
         w.count += int64(a)
         return
 }
 
 func (w *prodWriter) Close() error {
         if w.Writer == nil {
                 return nil
         }
 
-        return retry.Retry(w, retry.TransientOnly(retry.Default),
+        return retry.Retry(w, transient.Only(retry.Default),
                 w.Writer.Close,
                 func(err error, d time.Duration) {
                         log.Fields{
                                 log.ErrorKey: err,
                                 "delay":      d,
                                 "bucket":     w.bucket,
                                 "path":       w.relpath,
                         }.Warningf(w, "Transient error closing GS Writer. Retrying...")
                 })
 }
 
 func (w *prodWriter) Count() int64 {
         return w.count
 }