Add UMA Histogram Manager to Cronet.

components/cronet/android/histogram_manager.cc

Index: components/cronet/android/histogram_manager.cc
diff --git a/components/cronet/android/histogram_manager.cc b/components/cronet/android/histogram_manager.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c3390d77435d3bb3a715cb7750273e964942a13c
--- /dev/null
+++ b/components/cronet/android/histogram_manager.cc
@@ -0,0 +1,83 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/cronet/android/histogram_manager.h"
+
+#include <string>
+
+#include "base/android/jni_array.h"
+#include "base/memory/singleton.h"
+#include "base/metrics/histogram_delta_serialization.h"
+#include "base/metrics/histogram_samples.h"
+#include "base/metrics/histogram_snapshot_manager.h"
+#include "base/metrics/sample_map.h"
+#include "base/metrics/statistics_recorder.h"
+#include "components/metrics/metrics_hashes.h"
+#include "components/metrics/metrics_log.h"

[Alexei Svitkine (slow), 2014/12/10 15:19:31]

This is no longer needed. Please check the other includes too.

[ramant (doing other things), 2014/12/10 22:27:51]

Done.

+#include "components/metrics/proto/histogram_event.pb.h"
+
+#include "jni/HistogramManager_jni.h"
+
+using base::SampleCountIterator;

[Alexei Svitkine (slow), 2014/12/10 15:19:31]

This is no longer needed.

[ramant (doing other things), 2014/12/10 22:27:51]

Done.

+
+namespace cronet {
+
+static const char kCronetHistogramName[] = "cronet";

[Alexei Svitkine (slow), 2014/12/10 15:19:31]

This is not used.

[ramant (doing other things), 2014/12/10 22:27:51]

Done.

+
+// Explicitly register static JNI functions.
+bool HistogramManagerRegisterJni(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+HistogramManager::HistogramManager() : histogram_snapshot_manager_(this) {
+}
+
+HistogramManager::~HistogramManager() {
+}
+
+// static
+HistogramManager* HistogramManager::GetInstance() {
+  return Singleton<HistogramManager>::get();
+}
+
+void HistogramManager::RecordDelta(const base::HistogramBase& histogram,
+                                   const base::HistogramSamples& snapshot) {
+  metrics::RecordHistogramDelta(&uma_proto_, histogram_name, snapshot);
+}
+
+void HistogramManager::InconsistencyDetected(
+    base::HistogramBase::Inconsistency problem) {
+  UMA_HISTOGRAM_ENUMERATION("Histogram.InconsistenciesBrowser.Cronet",
+                            problem, base::HistogramBase::NEVER_EXCEEDED_VALUE);
+}
+
+void HistogramManager::UniqueInconsistencyDetected(
+    base::HistogramBase::Inconsistency problem) {
+  UMA_HISTOGRAM_ENUMERATION("Histogram.InconsistenciesBrowserUnique.Cronet",
+                            problem, base::HistogramBase::NEVER_EXCEEDED_VALUE);
+}
+
+void HistogramManager::InconsistencyDetectedInLoggedCount(int amount) {
+  UMA_HISTOGRAM_COUNTS("Histogram.InconsistentSnapshotBrowser.Cronet",
+                       std::abs(amount));
+}
+
+void HistogramManager::PrepareDeltas() {
+  histogram_snapshot_manager_->PrepareDeltas(
+      base::Histogram::kNoFlags, base::Histogram::kUmaTargetedHistogramFlag);
+}
+
+static jbyteArray GetHistogramDeltas(JNIEnv* env, jobject jcaller) {
+  HistogramManager* histogram_manager = HistogramManager::GetInstance();

[mef, 2014/12/10 15:06:52]

I think having it as singleton for initial CL is Ok, I can convert it to hang
off java object in the follow up CL.

[Alexei Svitkine (slow), 2014/12/10 15:19:31]

I agree, this is fine for now. Maybe add a TODO about it.

[ramant (doing other things), 2014/12/10 22:27:51]

Acknowledged.

[ramant (doing other things), 2014/12/10 22:27:51]

Done.

+  histogram_manager->PrepareDeltas();
+  int data_size = histogram_manager->uma_proto().ByteSize();

[Alexei Svitkine (slow), 2014/12/10 15:19:31]

|uma_proto| should be cleared between calls.

[ramant (doing other things), 2014/12/10 22:27:51]

Done.

+  std::vector<uint8> data(data_size);
+  if (histogram_manager->uma_proto().SerializeToArray(&data[0], data_size)) {
+    return base::android::ToJavaByteArray(env, &data[0], data_size).Release();
+  }
+
+  return NULL;
+}
+
+}  // namespace cronet