Make cc::DrawingDisplayItem hold a const SkPicture.

cc/playback/drawing_display_item.cc

 // Copyright 2014 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.
 
 #include "cc/playback/drawing_display_item.h"
 
 #include <stddef.h>
 
 #include <string>
 
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "base/values.h"
 #include "cc/debug/picture_debug_util.h"
 #include "cc/proto/display_item.pb.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkData.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "third_party/skia/include/core/SkStream.h"
 #include "third_party/skia/include/utils/SkPictureUtils.h"
 #include "ui/gfx/skia_util.h"
 
 namespace cc {
 
 DrawingDisplayItem::DrawingDisplayItem() {}
 
-DrawingDisplayItem::DrawingDisplayItem(skia::RefPtr<SkPicture> picture) {
+DrawingDisplayItem::DrawingDisplayItem(skia::RefPtr<const SkPicture> picture) {
   SetNew(std::move(picture));
 }
 
 DrawingDisplayItem::DrawingDisplayItem(const proto::DisplayItem& proto) {
   DCHECK_EQ(proto::DisplayItem::Type_Drawing, proto.type());
 
   skia::RefPtr<SkPicture> picture;
   const proto::DrawingDisplayItem& details = proto.drawing_item();
   if (details.has_picture()) {
     SkMemoryStream stream(details.picture().data(), details.picture().size());
 
     // TODO(dtrainor, nyquist): Add an image decoder.
     picture = skia::AdoptRef(SkPicture::CreateFromStream(&stream, nullptr));
   }
 
   SetNew(std::move(picture));
 }
 
 DrawingDisplayItem::DrawingDisplayItem(const DrawingDisplayItem& item) {
   item.CloneTo(this);
 }
 
 DrawingDisplayItem::~DrawingDisplayItem() {
 }
 
-void DrawingDisplayItem::SetNew(skia::RefPtr<SkPicture> picture) {
+void DrawingDisplayItem::SetNew(skia::RefPtr<const SkPicture> picture) {
   picture_ = std::move(picture);
 }
 
 void DrawingDisplayItem::ToProtobuf(proto::DisplayItem* proto) const {
   proto->set_type(proto::DisplayItem::Type_Drawing);
 
   proto::DrawingDisplayItem* details = proto->mutable_drawing_item();
 
   // Just use skia's serialize() method for now.
   if (picture_) {
@@ skipping 66 matching lines @@
 
 int DrawingDisplayItem::ApproximateOpCount() const {
   return picture_->approximateOpCount();
 }
 
 bool DrawingDisplayItem::IsSuitableForGpuRasterization() const {
   return picture_->suitableForGpuRasterization(NULL);
 }
 
 }  // namespace cc