2 files changed, 5 insertions, 0 deletions
diff --git a/chrome/common/histogram_synchronizer.cc b/chrome/common/histogram_synchronizer.cc
index 2a7e09a..9aeff5e 100644
--- a/chrome/common/histogram_synchronizer.cc
+++ b/chrome/common/histogram_synchronizer.cc
@@ -240,6 +240,9 @@ int HistogramSynchronizer::GetNextAvaibleSequenceNumber(
     RendererHistogramRequester requester) {
   AutoLock auto_lock(lock_);
   ++next_available_sequence_number_;
+  if (0 > next_available_sequence_number_)  // We wrapped around.
+    next_available_sequence_number_ = kReservedSequenceNumber + 1;
+  DCHECK(next_available_sequence_number_ != kReservedSequenceNumber);
   if (requester == ASYNC_HISTOGRAMS) {
     async_sequence_number_ = next_available_sequence_number_;
     async_renderers_pending_ = 0;
diff --git a/chrome/common/histogram_synchronizer.h b/chrome/common/histogram_synchronizer.h
index 35e965e..1190555 100644
--- a/chrome/common/histogram_synchronizer.h
+++ b/chrome/common/histogram_synchronizer.h
@@ -26,6 +26,8 @@ class HistogramSynchronizer : public
     SYNCHRONOUS_HISTOGRAMS
   };
 
+  static const int kReservedSequenceNumber = 0;
+
   HistogramSynchronizer();
 
   ~HistogramSynchronizer();