Revert "Add UMA Histogram Manager to Cronet."

components/metrics/metrics_log.cc

Index: components/metrics/metrics_log.cc
diff --git a/components/metrics/metrics_log.cc b/components/metrics/metrics_log.cc
index fdfe3056c796e3efae1cb99dde94714b51cb7ae8..2ea6f89eab4bdf7bd419d566910725a4fafbf958 100644
--- a/components/metrics/metrics_log.cc
+++ b/components/metrics/metrics_log.cc
@@ -23,7 +23,6 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/sys_info.h"
 #include "base/time/time.h"
-#include "components/metrics/histogram_encoder.h"
 #include "components/metrics/metrics_hashes.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/metrics/metrics_provider.h"
@@ -179,7 +178,36 @@ void MetricsLog::RecordUserAction(const std::string& key) {
 void MetricsLog::RecordHistogramDelta(const std::string& histogram_name,
                                       const base::HistogramSamples& snapshot) {
   DCHECK(!closed_);
-  EncodeHistogramDelta(histogram_name, snapshot, &uma_proto_);
+  DCHECK_NE(0, snapshot.TotalCount());
+
+  // We will ignore the MAX_INT/infinite value in the last element of range[].
+
+  HistogramEventProto* histogram_proto = uma_proto_.add_histogram_event();
+  histogram_proto->set_name_hash(Hash(histogram_name));
+  histogram_proto->set_sum(snapshot.sum());
+
+  for (scoped_ptr<SampleCountIterator> it = snapshot.Iterator(); !it->Done();
+       it->Next()) {
+    base::Histogram::Sample min;
+    base::Histogram::Sample max;
+    base::Histogram::Count count;
+    it->Get(&min, &max, &count);
+    HistogramEventProto::Bucket* bucket = histogram_proto->add_bucket();
+    bucket->set_min(min);
+    bucket->set_max(max);
+    bucket->set_count(count);
+  }
+
+  // Omit fields to save space (see rules in histogram_event.proto comments).
+  for (int i = 0; i < histogram_proto->bucket_size(); ++i) {
+    HistogramEventProto::Bucket* bucket = histogram_proto->mutable_bucket(i);
+    if (i + 1 < histogram_proto->bucket_size() &&
+        bucket->max() == histogram_proto->bucket(i + 1).min()) {
+      bucket->clear_max();
+    } else if (bucket->max() == bucket->min() + 1) {
+      bucket->clear_min();
+    }
+  }
 }
 
 void MetricsLog::RecordStabilityMetrics(