Update APIs to use new Google cloud paths.

common/gcloud/gs/gs.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 (
         "fmt"
         "io"
         "net/http"
         "time"
 
         "github.com/luci/luci-go/common/errors"
         log "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/retry"
+
+        gs "cloud.google.com/go/storage"
         "golang.org/x/net/context"
         "google.golang.org/api/googleapi"
-        "google.golang.org/cloud"
-        gs "google.golang.org/cloud/storage"
+        "google.golang.org/api/option"
 )
 
 var (
         // ReadWriteScopes is the set of scopes needed for read/write Google Storage
         // access.
         ReadWriteScopes = []string{gs.ScopeReadWrite}
 
         // ReadOnlyScopes is the set of scopes needed for read/write Google Storage
         // read-only access.
         ReadOnlyScopes = []string{gs.ScopeReadOnly}
@@ skipping 160 matching lines @@
                 return nil
         }, func(err error, d time.Duration) {
                 log.Fields{
                         log.ErrorKey: err,
                         "delay":      d,
                 }.Warningf(c, "Transient error deleting file. Retrying...")
         })
 }
 
 func (c *prodClient) newClient() (*gs.Client, error) {
-        var optsArray [1]cloud.ClientOption
+        var optsArray [1]option.ClientOption
         opts := optsArray[:0]
         if c.rt != nil {
-                opts = append(opts, cloud.WithBaseHTTP(&http.Client{
+                opts = append(opts, option.WithHTTPClient(&http.Client{
                         Transport: c.rt,
                 }))
         }
         return gs.NewClient(c, opts...)
 }
 
 func (c *prodClient) handleForPath(p Path) (*gs.ObjectHandle, error) {
         bucket, filename, err := splitPathErr(p)
         if err != nil {
                 return nil, err
@@ skipping 16 matching lines @@
         // The storage library doesn't return gs.ErrObjectNotExist when Delete
         // returns a 404. Catch that explicitly.
         if t, ok := err.(*googleapi.Error); ok {
                 switch t.Code {
                 case http.StatusNotFound:
                         return true
                 }
         }
         return false
 }