278 struct PersistentHistogramAllocator::PersistentHistogramData {  struct in base::PersistentHistogramAllocator
280   static constexpr uint32_t kPersistentTypeId = 0xF1645910 + 3;
283   static constexpr size_t kExpectedInstanceSize =
286   int32_t histogram_type;
287   int32_t flags;
288   int32_t minimum;
289   int32_t maximum;
290   uint32_t bucket_count;
291   PersistentMemoryAllocator::Reference ranges_ref;
292   uint32_t ranges_checksum;
293   std::atomic<PersistentMemoryAllocator::Reference> counts_ref;
294   HistogramSamples::Metadata samples_metadata;
295   HistogramSamples::Metadata logged_metadata;
300   char name[sizeof(uint64_t)];  // Force 64-bit alignment on 32-bit builds.