Fix overflow when logging MaxInt32 to a sparse histogram.

base/metrics/persistent_sample_map_unittest.cc

 // Copyright (c) 2016 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/persistent_sample_map.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/persistent_histogram_allocator.h"
@@ skipping 146 matching lines @@
   HistogramSamples::LocalMetadata meta;
   PersistentSampleMap samples(1, allocator.get(), &meta);
   samples.Accumulate(1, 100);
   samples.Accumulate(2, 200);
   samples.Accumulate(4, -300);
   samples.Accumulate(5, 0);
 
   std::unique_ptr<SampleCountIterator> it = samples.Iterator();
 
   HistogramBase::Sample min;
-  HistogramBase::Sample max;
+  int64_t max;
   HistogramBase::Count count;
 
   it->Get(&min, &max, &count);
   EXPECT_EQ(1, min);
   EXPECT_EQ(2, max);
   EXPECT_EQ(100, count);
   EXPECT_FALSE(it->GetBucketIndex(NULL));
 
   it->Next();
   it->Get(&min, &max, &count);
@@ skipping 29 matching lines @@
   samples2.Accumulate(5, 1);
   samples2.Accumulate(20, 4);
   samples2.Accumulate(25, 5);
 
   samples1.Subtract(samples2);
 
   std::unique_ptr<SampleCountIterator> it = samples1.Iterator();
   EXPECT_FALSE(it->Done());
 
   HistogramBase::Sample min;
-  HistogramBase::Sample max;
+  int64_t max;
   HistogramBase::Count count;
 
   it->Get(&min, &max, &count);
   EXPECT_EQ(10, min);
   EXPECT_EQ(11, max);
   EXPECT_EQ(2, count);
 
   it->Next();
   EXPECT_FALSE(it->Done());
 
@@ skipping 10 matching lines @@
   std::unique_ptr<PersistentHistogramAllocator> allocator =
       CreateHistogramAllocator(64 << 10);  // 64 KiB
   HistogramSamples::LocalMetadata meta;
   PersistentSampleMap samples(1, allocator.get(), &meta);
 
   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(1, 100);
   it = samples.Iterator();
   EXPECT_FALSE(it->Done());
 }
 
 }  // namespace
 }  // namespace base