Fix overflow when logging MaxInt32 to a sparse histogram.

base/metrics/sample_vector_unittest.cc

 // 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.
 
 #include "base/metrics/sample_vector.h"
 
 #include <limits.h>
 #include <stddef.h>
 
 #include <memory>
@@ skipping 197 matching lines @@
   std::vector<HistogramBase::Count> counts(3);
   counts[0] = 1;
   counts[1] = 0;  // Iterator will bypass this empty bucket.
   counts[2] = 2;
 
   // BucketRanges can have larger size than counts.
   SampleVectorIterator it(&counts, &ranges);
   size_t index;
 
   HistogramBase::Sample min;
-  HistogramBase::Sample max;
+  int64_t max;
   HistogramBase::Count count;
   it.Get(&min, &max, &count);
   EXPECT_EQ(0, min);
   EXPECT_EQ(1, max);
   EXPECT_EQ(1, count);
   EXPECT_TRUE(it.GetBucketIndex(&index));
   EXPECT_EQ(0u, index);
 
   it.Next();
   it.Get(&min, &max, &count);
@@ skipping 35 matching lines @@
   ranges.set_range(2, 2);
   ranges.set_range(3, 3);
   ranges.set_range(4, INT_MAX);
   SampleVector samples(1, &ranges);
 
   std::unique_ptr<SampleCountIterator> it = samples.Iterator();
 
   EXPECT_TRUE(it->Done());
 
   HistogramBase::Sample min;
-  HistogramBase::Sample max;
+  int64_t max;
   HistogramBase::Count count;
   EXPECT_DCHECK_DEATH(it->Get(&min, &max, &count));
 
   EXPECT_DCHECK_DEATH(it->Next());
 
   samples.Accumulate(2, 100);
   it = samples.Iterator();
   EXPECT_FALSE(it->Done());
 }
 
 }  // namespace
 }  // namespace base