Add UMA Histogram Manager to Cronet.

components/cronet/android/histogram_manager.h

+// 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.
+
+#ifndef COMPONENTS_CRONET_ANDROID_CRONET_HISTOGRAM_MANAGER_H_
+#define COMPONENTS_CRONET_ANDROID_CRONET_HISTOGRAM_MANAGER_H_
+
+#include <jni.h>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/macros.h"
+
+namespace cronet {
+
+bool HistogramManagerRegisterJni(JNIEnv* env);
+
+// A HistogramManager instance is created by Android.  It is the central
+// controller for the acquisition of log data, and the automatic transmission of
+// that log data to an external server.
+class HistogramManager {

[Alexei Svitkine (slow), 2014/12/11 20:09:09]

Remove? Since its in the metrics component now?

[ramant (doing other things), 2014/12/11 20:23:53]

Haven't tested this code on cronet.  Added GetHistogramDeltas function
prototype.

+ public:
+  HistogramManager();
+  ~HistogramManager();
+
+  // Snapshot all histograms to record the delta into |uma_proto_| and then
+  // returns the serialized protobuf representation of the record.
+  std::vector<uint8> GetDeltas();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HistogramManager);
+};
+
+}  // namespace cronet
+
+#endif  // COMPONENTS_CRONET_ANDROID_CRONET_HISTOGRAM_MANAGER_H_