[blimp] Add SkPicture caching support.

cc/test/picture_cache_model.cc

+// Copyright 2016 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/test/picture_cache_model.h"
+
+#include "base/logging.h"
+#include "third_party/skia/include/core/SkData.h"
+#include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/core/SkStream.h"
+
+class SkPixelSerializer;
+
+namespace cc {
+namespace {
+
+sk_sp<SkPicture> CopySkPicture(const SkPicture* picture) {
+  SkDynamicMemoryWStream write_stream;
+  picture->serialize(&write_stream, nullptr);
+  DCHECK_GT(write_stream.bytesWritten(), 0u);
+
+  sk_sp<SkData> data(write_stream.copyToData());
+
+  SkMemoryStream read_stream(data);
+  return SkPicture::MakeFromStream(&read_stream, nullptr);
+}
+
+}  // namespace
+
+PictureCacheModel::PictureCacheModel() = default;
+
+PictureCacheModel::~PictureCacheModel() = default;
+
+void PictureCacheModel::AddPicture(const SkPicture* picture) {
+  sk_sp<SkPicture> picture_copy = CopySkPicture(picture);
+  pictures_.insert(std::make_pair(picture->uniqueID(), picture_copy));
+}
+
+sk_sp<const SkPicture> PictureCacheModel::GetPicture(uint32_t unique_id) {

[vmpstr, 2016/06/24 18:58:32]

Does this need to be sk_sp? Can you just return a raw ptr?

[nyquist, 2016/06/24 20:31:23]

That makes all the tests using it crash. It ends up as sk_sp<const SkPicture> in
drawing display item.

+  if (pictures_.find(unique_id) == pictures_.end())
+    return nullptr;
+
+  return pictures_.find(unique_id)->second;
+}
+
+}  // namespace cc