Update APIs to use new Google cloud paths.

grpc/cmd/cproto/main.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 (
         "flag"
         "fmt"
         "go/build"
@@ skipping 26 matching lines @@
                 "desc",
                 "",
                 "Writes a FileDescriptorSet file containing all the the .proto files and their transitive dependencies",
         )
 )
 
 func resolveGoogleProtobufPackages(c context.Context) (map[string]string, error) {
         const (
                 protoPrefix = "google/protobuf/"
                 pkgPath     = "github.com/luci/luci-go/common/proto/google"
+                descPkgPath = "google.golang.org/genproto/protobuf"
         )
         var result = map[string]string{
-                protoPrefix + "descriptor.proto": pkgPath + "/descriptor", //snowflake
+                protoPrefix + "descriptor.proto": descPkgPath, //snowflake
         }
 
         pkg, err := build.Import(pkgPath, "", build.FindOnly)
         if err != nil {
                 return nil, err
         }
         protoFiles, err := findProtoFiles(pkg.Dir)
         if err != nil {
                 return nil, err
         }
@@ skipping 221 matching lines @@
         src := strings.TrimSuffix(dir, pkg)
         src = path.Clean(src)
         goPaths := strings.Split(os.Getenv("GOPATH"), string(filepath.ListSeparator))
         for _, goPath := range goPaths {
                 if filepath.Join(goPath, "src") == src {
                         return true, nil
                 }
         }
         return false, nil
 }