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>
+
+#include "content/public/browser/browser_thread.h"
+
+namespace metrics {
+
+LeakDetector::LeakReport::LeakReport() {}
+
+LeakDetector::LeakReport::~LeakReport() {}
+
+LeakDetector::LeakDetector(float sampling_rate,
+                           int max_stack_depth,

[jochen (gone - plz use gerrit), 2016/02/24 08:05:22]

what does a negative value mean here?

[Simon Que, 2016/02/24 21:28:34]

Changed to size_t.

+                           uint64_t analysis_interval_bytes,
+                           int size_suspicion_threshold,
+                           int call_stack_suspicion_threshold)

[jochen (gone - plz use gerrit), 2016/02/24 08:05:22]

and for those two? what do those values mean anyways?

[Simon Que, 2016/02/24 21:28:34]

See comment in header file for meaning.

Changed to uint32_t.

+    : weak_factory_(this) {}
+
+LeakDetector::LeakDetector() : LeakDetector(1.0f, 4, 32 * 1024 * 1024, 4, 4) {}

[jochen (gone - plz use gerrit), 2016/02/24 08:05:22]

can you please define constants for these values, so they have names?

[Simon Que, 2016/02/24 21:28:35]

Done.

+
+LeakDetector::~LeakDetector() {}
+
+void LeakDetector::AddObserver(Observer* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  observers_.AddObserver(observer);
+}
+
+void LeakDetector::RemoveObserver(Observer* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  observers_.RemoveObserver(observer);
+}
+
+void LeakDetector::NotifyObservers(const std::vector<LeakReport>& reports) {
+  if (!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI)) {
+    content::BrowserThread::PostTask(
+        content::BrowserThread::UI, FROM_HERE,
+        base::Bind(&LeakDetector::NotifyObservers, weak_factory_.GetWeakPtr(),
+                   reports));
+    return;
+  }
+
+  for (const LeakReport& report : reports) {
+    FOR_EACH_OBSERVER(Observer, observers_, OnLeakFound(report));
+  }
+}
+
+}  // namespace metrics