Update APIs to use new Google cloud paths.

grpc/cmd/rpc/descriptor.go

 // Copyright 2016 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 main
 
 import (
         "fmt"
         "strings"
 
+        "github.com/luci/luci-go/common/proto/google/descutil"
+
         "golang.org/x/net/context"
 
-        "github.com/luci/luci-go/common/proto/google/descriptor"
         "github.com/luci/luci-go/grpc/discovery"
         "github.com/luci/luci-go/grpc/prpc"
+        "google.golang.org/genproto/protobuf"
 )
 
 type serverDescription struct {
         *discovery.DescribeResponse
 }
 
 func loadDescription(c context.Context, client *prpc.Client) (*serverDescription, error) {
         dc := discovery.NewDiscoveryPRPCClient(client)
         res, err := dc.Describe(c, &discovery.Void{})
         if err != nil {
                 return nil, fmt.Errorf("could not load server description: %s", err)
         }
 
         return &serverDescription{res}, nil
 }
 
 // resolveInputMessage resolves input message type of a method.
 func (d *serverDescription) resolveInputMessage(service, method string) (*descriptor.DescriptorProto, error) {
-        _, obj, _ := d.Description.Resolve(service)
+        _, obj, _ := descutil.Resolve(d.Description, service)
         serviceDesc, ok := obj.(*descriptor.ServiceDescriptorProto)
         if !ok {
                 return nil, fmt.Errorf("service %q not found", service)
         }
 
-        mi := serviceDesc.FindMethod(method)
+        mi := descutil.FindMethodForService(serviceDesc, method)
         if mi == -1 {
                 return nil, fmt.Errorf("method %q in service %q not found", method, service)
         }
 
         msgName := serviceDesc.Method[mi].GetInputType()
         msgName = strings.TrimPrefix(msgName, ".")
         return d.resolveMessage(msgName)
 }
 
 func (d *serverDescription) resolveMessage(name string) (*descriptor.DescriptorProto, error) {
-        _, obj, _ := d.Description.Resolve(name)
+        _, obj, _ := descutil.Resolve(d.Description, name)
         msg, ok := obj.(*descriptor.DescriptorProto)
         if !ok {
                 return nil, fmt.Errorf("message %q not found", name)
         }
         return msg, nil
 }