Consolidate gogo/protobuf dependencies under our own protobuf package

This would make gogo/protobuf migration easier.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

protobuf/any.go

@@ -17,11 +17,11 @@
 package protobuf
 
 import (
+	"github.com/containerd/containerd/protobuf/types"
 	"github.com/containerd/typeurl"
-	"github.com/gogo/protobuf/types"
 )
 
-// FromAny converts typeurl.Any to github.com/gogo/protobuf/types.Any.
+// FromAny converts typeurl.Any to github.com/containerd/containerd/protobuf/types.Any.
 func FromAny(from typeurl.Any) *types.Any {
 	if from == nil {
 		return nil
@@ -37,7 +37,7 @@ func FromAny(from typeurl.Any) *types.Any {
 	}
 }
 
-// FromAny converts an arbitrary interface to github.com/gogo/protobuf/types.Any.
+// FromAny converts an arbitrary interface to github.com/containerd/containerd/protobuf/types.Any.
 func MarshalAnyToProto(from interface{}) (*types.Any, error) {
 	any, err := typeurl.MarshalAny(from)
 	if err != nil {

protobuf/proto/proto.go

@@ -0,0 +1,30 @@
+/*
+   Copyright The containerd Authors.
+
+   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 proto provides convinient aliases that make google.golang.org/protobuf migration easier.
+package proto
+
+import (
+	gogo "github.com/gogo/protobuf/proto"
+)
+
+func Marshal(input gogo.Message) ([]byte, error) {
+	return gogo.Marshal(input)
+}
+
+func Unmarshal(input []byte, output gogo.Message) error {
+	return gogo.Unmarshal(input, output)
+}

protobuf/types/types.go

@@ -0,0 +1,26 @@
+/*
+   Copyright The containerd Authors.
+
+   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 types provides convinient aliases that make google.golang.org/protobuf migration easier.
+package types
+
+import (
+	gogo "github.com/gogo/protobuf/types"
+)
+
+type Empty = gogo.Empty
+type Any = gogo.Any
+type FieldMask = gogo.FieldMask