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..68df285ff254d2679f152b8ef4cec436a4c203a7
--- /dev/null
+++ b/components/cronet/android/histogram_manager.cc
@@ -0,0 +1,76 @@
+// 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.h"
+#include "base/metrics/histogram_samples.h"
+
+#include "jni/HistogramManager_jni.h"
+
+namespace cronet {
+
+// 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(histogram_name, snapshot, &uma_proto_);
+}
+
+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() {
+  // Clear the protobuf between calls.
+  uma_proto_.Clear();
+  histogram_snapshot_manager_->PrepareDeltas(
+      base::Histogram::kNoFlags, base::Histogram::kUmaTargetedHistogramFlag);
+}
+
+static jbyteArray GetHistogramDeltas(JNIEnv* env, jobject jcaller) {
+  // TODO(mef): convert histogram_manager singleton to hang off java object.
+  HistogramManager* histogram_manager = HistogramManager::GetInstance();
+  histogram_manager->PrepareDeltas();
+  int data_size = histogram_manager->uma_proto().ByteSize();
+  std::vector<uint8> data(data_size);
+  if (histogram_manager->uma_proto().SerializeToArray(&data[0], data_size)) {

[Alexei Svitkine (slow), 2014/12/10 21:50:17]

I suggest making a method of HistogramManager that can serialize to
std::vector<uint8> which this function will call. Then, the unit test I
suggested in a previous comment can just test the C++ class directly and the
Java code will just be a wrapper over it.

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

Done. Will work with mef to write the unit test.

+    return base::android::ToJavaByteArray(env, &data[0], data_size).Release();
+  }
+
+  return NULL;
+}
+
+}  // namespace cronet