 dump's parent) to the
    // proportion of this dump's size which they (or their descendants) own.
    this.ownedBySiblingSizes = new Map();

    // Retention relationship between memory allocator dumps.
    this.retains = [];
    this.retainedBy = [];

    // Weak memory allocator dumps are removed from the model after import in
    // tr.model.GlobalMemoryDump.removeWeakDumps(). See
    // base::trace_event::MemoryAllocatorDump::Flags::WEAK in the Chromium
    // codebase.
    this.weak = false;

    // 