Fix overflow when logging MaxInt32 to a sparse histogram.

chrome/browser/ui/webui/task_scheduler_internals/task_scheduler_internals_ui.cc

Index: chrome/browser/ui/webui/task_scheduler_internals/task_scheduler_internals_ui.cc
diff --git a/chrome/browser/ui/webui/task_scheduler_internals/task_scheduler_internals_ui.cc b/chrome/browser/ui/webui/task_scheduler_internals/task_scheduler_internals_ui.cc
index 28efc762c3bb268f02edfe93b1278ad6087cf73b..79edccd40eceab121d01dcd904e3b2bf08fc53af 100644
--- a/chrome/browser/ui/webui/task_scheduler_internals/task_scheduler_internals_ui.cc
+++ b/chrome/browser/ui/webui/task_scheduler_internals/task_scheduler_internals_ui.cc
@@ -30,14 +30,18 @@ std::unique_ptr<base::Value> SnapshotHistogramToValue(
   std::unique_ptr<base::SampleCountIterator> iterator = samples->Iterator();
   while (!iterator->Done()) {
     base::HistogramBase::Sample min;
-    base::HistogramBase::Sample max;
+    int64_t max;
     base::HistogramBase::Count count;
     iterator->Get(&min, &max, &count);
 
     std::unique_ptr<base::DictionaryValue> bucket =
         base::MakeUnique<base::DictionaryValue>();
     bucket->SetInteger("min", min);
-    bucket->SetInteger("max", max);
+    // Note: DictionaryValue does not support 64-bit integer values. The static
+    // cast below is OK in this case because none of the histograms passed to
+    // this function should be logging MaxInt32 as a sparse histogram bucket,
+    // which is the only case max will exceed 32-bit range.
+    bucket->SetInteger("max", static_cast<int>(max));

[Ilya Sherman, 2017/05/02 21:37:49]

nit: Could this be a checked_cast?

[Alexei Svitkine (slow), 2017/05/03 15:21:53]

Done.

     bucket->SetInteger("count", count);
 
     values->Append(std::move(bucket));