Fix overflow when logging MaxInt32 to a sparse histogram.

base/metrics/sparse_histogram.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/sparse_histogram.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/metrics_hashes.h"
@@ skipping 225 matching lines @@
 
   // Determine how wide the largest bucket range is (how many digits to print),
   // so that we'll be able to right-align starts for the graphical bars.
   // Determine which bucket has the largest sample count so that we can
   // normalize the graphical bar-width relative to that sample count.
   Count largest_count = 0;
   Sample largest_sample = 0;
   std::unique_ptr<SampleCountIterator> it = snapshot->Iterator();
   while (!it->Done()) {
     Sample min;
-    Sample max;
+    int64_t max;
     Count count;
     it->Get(&min, &max, &count);
     if (min > largest_sample)
       largest_sample = min;
     if (count > largest_count)
       largest_count = count;
     it->Next();
   }
   size_t print_width = GetSimpleAsciiBucketRange(largest_sample).size() + 1;
 
   // iterate over each item and display them
   it = snapshot->Iterator();
   while (!it->Done()) {
     Sample min;
-    Sample max;
+    int64_t max;
     Count count;
     it->Get(&min, &max, &count);
 
     // value is min, so display it
     std::string range = GetSimpleAsciiBucketRange(min);
     output->append(range);
     for (size_t j = 0; range.size() + j < print_width + 1; ++j)
       output->push_back(' ');
 
     if (graph_it)
       WriteAsciiBucketGraph(count, largest_count, output);
     WriteAsciiBucketValue(count, scaled_total_count, output);
     output->append(newline);
     it->Next();
   }
 }
 
 void SparseHistogram::WriteAsciiHeader(const Count total_count,
                                        std::string* output) const {
   StringAppendF(output,
                 "Histogram: %s recorded %d samples",
                 histogram_name().c_str(),
                 total_count);
   if (flags())
     StringAppendF(output, " (flags = 0x%x)", flags());
 }
 
 }  // namespace base