Add support for converting cc::Region to and from protobuf.

cc/proto/cc_conversions.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_PROTO_CC_CONVERSIONS_H_
+#define CC_PROTO_CC_CONVERSIONS_H_
+
+#include "cc/base/cc_export.h"
+
+namespace cc {
+class Region;
+
+namespace proto {
+class Region;
+}  // namespace proto
+
+// TODO(dtrainor): Move these to a class and make them static
+// (crbug.com/548432).
+CC_EXPORT void RegionToProto(const Region& region, proto::Region* proto);
+CC_EXPORT Region RegionFromProto(const proto::Region& proto);
+
+}  // namespace cc
+
+#endif  // CC_PROTO_CC_CONVERSIONS_H_