Merge "Store previous buffer as a wp" into main

        uint32_t bufferTransform;

        bool transformToDisplayInverse;

        Region transparentRegionHint;

        std::shared_ptr<renderengine::ExternalTexture> previousBuffer;

        std::weak_ptr<renderengine::ExternalTexture> previousBuffer;

        std::shared_ptr<renderengine::ExternalTexture> buffer;

        sp<Fence> acquireFence;

        std::shared_ptr<FenceTime> acquireFenceTime;