Update GCS storage library to support GetObject API on gzipped objects (#6506)

Fixes #6280

vendor/google.golang.org/api/transport/grpc/go18.go

@@ -0,0 +1,26 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build go1.8
+
+package grpc
+
+import (
+	"go.opencensus.io/plugin/ocgrpc"
+	"google.golang.org/grpc"
+)
+
+func addOCStatsHandler(opts []grpc.DialOption) []grpc.DialOption {
+	return append(opts, grpc.WithStatsHandler(&ocgrpc.ClientHandler{}))
+}