Add ThreadChecker to HistogramSnapshotManager.

base/metrics/histogram_snapshot_manager.cc

Index: base/metrics/histogram_snapshot_manager.cc
diff --git a/base/metrics/histogram_snapshot_manager.cc b/base/metrics/histogram_snapshot_manager.cc
index a774ea6177c7da8ad8c95c9faded69c185502424..32702d8b3eb94a8800b4fe4f45f487ee4a26df74 100644
--- a/base/metrics/histogram_snapshot_manager.cc
+++ b/base/metrics/histogram_snapshot_manager.cc
@@ -35,6 +35,7 @@ void HistogramSnapshotManager::PrepareFinalDelta(
 void HistogramSnapshotManager::PrepareSamples(
     const HistogramBase* histogram,
     std::unique_ptr<HistogramSamples> samples) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(histogram_flattener_);
 
   // Get information known about this histogram. If it did not previously
@@ -93,20 +94,4 @@ void HistogramSnapshotManager::PrepareSamples(
     histogram_flattener_->RecordDelta(*histogram, *samples);
 }
 
-void HistogramSnapshotManager::InspectLoggedSamplesInconsistency(
-      const HistogramSamples& new_snapshot,
-      HistogramSamples* logged_samples) {
-  HistogramBase::Count discrepancy =
-      logged_samples->TotalCount() - logged_samples->redundant_count();
-  if (!discrepancy)
-    return;
-
-  histogram_flattener_->InconsistencyDetectedInLoggedCount(discrepancy);
-  if (discrepancy > Histogram::kCommonRaceBasedCountMismatch) {
-    // Fix logged_samples.
-    logged_samples->Subtract(*logged_samples);
-    logged_samples->Add(new_snapshot);
-  }
-}
-
 }  // namespace base