Add protobuf serialization to DisplayItemList

cc/proto/skia_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_SKIA_CONVERSIONS_H_
 #define CC_PROTO_SKIA_CONVERSIONS_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/proto/skregion.pb.h"
 #include "cc/proto/skxfermode.pb.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 
 class SkRegion;
 class SkRRect;
 class SkXferMode;
 
 namespace cc {
 
 namespace proto {
 class SkRRect;
 }
 
+// TODO(dtrainor): Move these to a class and make them static
+// (crbug.com/548432).
 CC_EXPORT SkRegion::Op SkRegionOpFromProto(proto::SkRegion::Op op);
 CC_EXPORT proto::SkRegion::Op SkRegionOpToProto(SkRegion::Op op);
 
 CC_EXPORT SkXfermode::Mode SkXfermodeModeFromProto(
     proto::SkXfermode::Mode mode);
 CC_EXPORT proto::SkXfermode::Mode SkXfermodeModeToProto(SkXfermode::Mode mode);
 
 CC_EXPORT void SkRRectToProto(const SkRRect& rect, proto::SkRRect* proto);
 CC_EXPORT SkRRect ProtoToSkRRect(const proto::SkRRect& proto);
 
 }  // namespace cc
 
 #endif  // CC_PROTO_SKIA_CONVERSIONS_H_