[blimp] Add SkPicture caching support.

blimp/client/feature/compositor/blimp_client_picture_cache.h

+// 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.
+
+#ifndef BLIMP_CLIENT_FEATURE_COMPOSITOR_BLIMP_CLIENT_PICTURE_CACHE_H_
+#define BLIMP_CLIENT_FEATURE_COMPOSITOR_BLIMP_CLIENT_PICTURE_CACHE_H_
+
+#include <stdint.h>
+#include <map>
+#include <memory>
+
+#include "base/logging.h"
+#include "base/macros.h"
+#include "blimp/common/compositor/blimp_picture_cache_registry.h"
+#include "cc/proto/picture_cache.h"
+#include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
+
+namespace blimp {
+namespace client {
+
+// BlimpClientPictureCache provides functionality for caching SkPictures once
+// they are received from the engine, and cleaning up once the pictures are no
+// longer in use. It is required to update this cache when an SkPicture starts
+// being used and when it is not longer in use by calling
+// MarkPictureForRegistration and MarkPictureForUnregistration respectively.
+class BlimpClientPictureCache : public cc::ClientPictureCache {
+ public:
+  explicit BlimpClientPictureCache(
+      SkPicture::InstallPixelRefProc pixel_deserializer);
+  ~BlimpClientPictureCache() override;
+
+  // cc::ClientPictureCache implementation.
+  sk_sp<const SkPicture> GetPicture(uint32_t engine_picture_id) override;
+  void ApplyCacheUpdate(const cc::PictureCacheUpdate& cache_update) override;
+  void Flush() override;
+  void MarkPictureForUnregistration(uint32_t engine_picture_id) override;
+  void MarkPictureForRegistration(uint32_t engine_picture_id) override;
+
+ private:
+  // A function pointer valid to use for deserializing images when
+  // using SkPicture::CreateFromStream to create an SkPicture from a stream.
+  SkPicture::InstallPixelRefProc pixel_deserializer_;
+
+  // The current cache of SkPictures. The key is the unique ID used by the
+  // engine, and the value is the SkPicture itself.
+  std::map<uint32_t, sk_sp<SkPicture>> pictures_;

[vmpstr, 2016/06/01 00:10:56]

Should the value be sk_sp<const SkPicture>?

[nyquist, 2016/06/04 00:24:57]

Done.

+
+  // A ref-counted registry of SkPictures that are currently in use.
+  BlimpPictureCacheRegistry registry_;
+
+#if DCHECK_IS_ON()
+  // A set of the items that were added when the last cache update was applied.
+  // Used for verifying that the calculation from the registry matches the
+  // expectations.
+  std::set<uint32_t> last_added_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(BlimpClientPictureCache);
+};
+
+}  // namespace client
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_FEATURE_COMPOSITOR_BLIMP_CLIENT_PICTURE_CACHE_H_