Update vendor

vendor/github.com/google/go-containerregistry/pkg/v1/layer.go

@@ -0,0 +1,42 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// 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.
+
+package v1
+
+import (
+	"io"
+
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+// Layer is an interface for accessing the properties of a particular layer of a v1.Image
+type Layer interface {
+	// Digest returns the Hash of the compressed layer.
+	Digest() (Hash, error)
+
+	// DiffID returns the Hash of the uncompressed layer.
+	DiffID() (Hash, error)
+
+	// Compressed returns an io.ReadCloser for the compressed layer contents.
+	Compressed() (io.ReadCloser, error)
+
+	// Uncompressed returns an io.ReadCloser for the uncompressed layer contents.
+	Uncompressed() (io.ReadCloser, error)
+
+	// Size returns the compressed size of the Layer.
+	Size() (int64, error)
+
+	// MediaType returns the media type of the Layer.
+	MediaType() (types.MediaType, error)
+}