metrics: Add leak detector controller in Chrome OS metrics system

components/metrics/leak_detector/leak_detector.cc

+// 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.
+
+#include "components/metrics/leak_detector/leak_detector.h"
+
+#include <algorithm>
+
+namespace metrics {
+
+LeakDetector::LeakReport::LeakReport() {}
+
+LeakDetector::LeakReport::~LeakReport() {}
+
+LeakDetector::LeakDetector(float sampling_rate,
+                           int max_stack_depth,
+                           uint64_t analysis_interval_bytes,
+                           int size_suspicion_threshold,
+                           int call_stack_suspicion_threshold) {}
+
+LeakDetector::~LeakDetector() {}
+
+bool LeakDetector::AddObserver(Observer* observer) {
+  observers_.push_back(observer);
+  return true;

[Alexei Svitkine (slow), 2016/02/10 20:16:58]

If you always return true, why have a return value?

[Simon Que, 2016/02/11 01:45:37]

Changing them both to return void, esp in light of using ObserverList.

+}
+
+bool LeakDetector::RemoveObserver(Observer* observer) {
+  auto iter = std::find(observers_.begin(), observers_.end(), observer);
+  if (iter == observers_.end())
+    return false;
+  observers_.erase(iter);
+  return true;
+}
+
+void LeakDetector::NotifyObservers(const std::vector<LeakReport>& reports) {
+  for (LeakDetector::Observer* observer : observers_) {
+    for (const LeakReport& report : reports) {
+      observer->OnLeakFound(report);
+    }
+  }
+}
+
+}  // namespace metrics