Fix overflow when logging MaxInt32 to a sparse histogram.

base/metrics/sample_vector.h

 // Copyright (c) 2012 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.
 
 // SampleVector implements HistogramSamples interface. It is used by all
 // Histogram based classes to store samples.
 
 #ifndef BASE_METRICS_SAMPLE_VECTOR_H_
 #define BASE_METRICS_SAMPLE_VECTOR_H_
 
@@ skipping 144 matching lines @@
                        const BucketRanges* bucket_ranges);
   SampleVectorIterator(const HistogramBase::AtomicCount* counts,
                        size_t counts_size,
                        const BucketRanges* bucket_ranges);
   ~SampleVectorIterator() override;
 
   // SampleCountIterator implementation:
   bool Done() const override;
   void Next() override;
   void Get(HistogramBase::Sample* min,
-           HistogramBase::Sample* max,
+           int64_t* max,
            HistogramBase::Count* count) const override;
 
   // SampleVector uses predefined buckets, so iterator can return bucket index.
   bool GetBucketIndex(size_t* index) const override;
 
  private:
   void SkipEmptyBuckets();
 
   const HistogramBase::AtomicCount* counts_;
   size_t counts_size_;
   const BucketRanges* bucket_ranges_;
 
   size_t index_;
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_SAMPLE_VECTOR_H_