metrics: Add leak detector controller in Chrome OS metrics system

chrome/browser/metrics/leak_detector_controller.h

+// Copyright 2016 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 CHROME_BROWSER_METRICS_LEAK_DETECTOR_CONTROLLER_H_
+#define CHROME_BROWSER_METRICS_LEAK_DETECTOR_CONTROLLER_H_
+
+#include <vector>
+
+#include "base/macros.h"
+#include "components/metrics/leak_detector/leak_detector.h"
+#include "components/metrics/proto/memory_leak_report.pb.h"
+
+namespace metrics {
+
+// This class initializes the LeakDetector on the browser process and registers
+// itself to be notified of leak reports.
+class LeakDetectorController : public LeakDetector::Observer {
+ public:
+  LeakDetectorController();
+  ~LeakDetectorController();
+
+  // Stores a new leak report in |stored_reports_|.

[Alexei Svitkine (slow), 2016/02/12 16:17:42]

This comment should just be:

// LeakDetector::Observer:

[Simon Que, 2016/02/12 19:00:07]

Will make this change once I know what to do regarding the other comments.

[Simon Que, 2016/02/17 20:49:33]

Done.

+  void OnLeakFound(const LeakDetector::LeakReport& report) override;

[Alexei Svitkine (slow), 2016/02/12 16:17:42]

Move this to private section.

[Simon Que, 2016/02/12 19:00:07]

What about the unit test? It calls this func. How about creating a derived class
that exposes these functions, like here:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/met...

[Alexei Svitkine (slow), 2016/02/17 16:06:30]

Derived class that exposes these functions SGTM.

[Simon Que, 2016/02/17 20:49:33]

Done.

+
+  // Retrieves all reports in |stored_reports_|, moving them to |*reports|.
+  // |stored_reports_| is empty afterwards.
+  void GetLeakReports(std::vector<MemoryLeakReportProto>* reports);
+
+ private:
+  // Leak detector interface object.
+  LeakDetector detector_;
+
+  // All leak reports received through OnLeakFound() are stored in protobuf
+  // format.
+  std::vector<MemoryLeakReportProto> stored_reports_;
+
+  DISALLOW_COPY_AND_ASSIGN(LeakDetectorController);
+};
+
+}  // namespace metrics
+
+#endif  // CHROME_BROWSER_METRICS_LEAK_DETECTOR_CONTROLLER_H_