Use ThreadChecker in HistogramDeltaSerialization class.

base/metrics/histogram_delta_serialization.cc

Index: base/metrics/histogram_delta_serialization.cc
diff --git a/base/metrics/histogram_delta_serialization.cc b/base/metrics/histogram_delta_serialization.cc
index e4aad13ac229aea13033635f8221f2e62dd96958..f2b825b6d3121c4d8d0fd85f0a49c6df04fe4822 100644
--- a/base/metrics/histogram_delta_serialization.cc
+++ b/base/metrics/histogram_delta_serialization.cc
@@ -61,6 +61,8 @@ HistogramDeltaSerialization::~HistogramDeltaSerialization() {
 
 void HistogramDeltaSerialization::PrepareAndSerializeDeltas(
     std::vector<std::string>* serialized_deltas) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
   serialized_deltas_ = serialized_deltas;
   // Note: Before serializing, we set the kIPCSerializationSourceFlag for all
   // the histograms, so that the receiving process can distinguish them from the
@@ -84,6 +86,7 @@ void HistogramDeltaSerialization::DeserializeAndAddSamples(
 void HistogramDeltaSerialization::RecordDelta(
     const HistogramBase& histogram,
     const HistogramSamples& snapshot) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(0, snapshot.TotalCount());
 
   Pickle pickle;
@@ -95,16 +98,22 @@ void HistogramDeltaSerialization::RecordDelta(
 
 void HistogramDeltaSerialization::InconsistencyDetected(
     HistogramBase::Inconsistency problem) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
   inconsistencies_histogram_->Add(problem);
 }
 
 void HistogramDeltaSerialization::UniqueInconsistencyDetected(
     HistogramBase::Inconsistency problem) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
   inconsistencies_unique_histogram_->Add(problem);
 }
 
 void HistogramDeltaSerialization::InconsistencyDetectedInLoggedCount(
     int amount) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
   inconsistent_snapshot_histogram_->Add(std::abs(amount));
 }