232 struct PersistentHistogramAllocator::PersistentHistogramData {  struct in base::PersistentHistogramAllocator
234   static constexpr uint32_t kPersistentTypeId = 0xF1645910 + 3;
237   static constexpr size_t kExpectedInstanceSize =
240   int32_t histogram_type;
241   int32_t flags;
242   int32_t minimum;
243   int32_t maximum;
244   uint32_t bucket_count;
245   PersistentMemoryAllocator::Reference ranges_ref;
246   uint32_t ranges_checksum;
247   subtle::Atomic32 counts_ref;  // PersistentMemoryAllocator::Reference
248   HistogramSamples::Metadata samples_metadata;
249   HistogramSamples::Metadata logged_metadata;
254   char name[sizeof(uint64_t)];  // Force 64-bit alignment on 32-bit builds.