metrics: Add leak detector controller in Chrome OS metrics system

chrome/browser/metrics/leak_detector_controller.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 "chrome/browser/metrics/leak_detector_controller.h"
+
+#include <algorithm>
+
+#include "base/logging.h"
+
+namespace metrics {
+
+namespace {
+
+// Default parameters for LeakDetector.
+const float kSamplingRate = 1.0f / 256;
+const int kMaxStackDepth = 4;
+const uint64_t kAnalysisIntervalBytes = 32 * 1024 * 1024;
+const int kSizeSuspicionThreshold = 4;
+const int kCallStackSuspicionThreshold = 4;
+
+}  // namespace
+
+LeakDetectorController::LeakDetectorController()
+    : detector_(kSamplingRate,
+                kMaxStackDepth,
+                kAnalysisIntervalBytes,
+                kSizeSuspicionThreshold,
+                kCallStackSuspicionThreshold) {
+  detector_.AddObserver(this);
+}
+
+LeakDetectorController::~LeakDetectorController() {
+  detector_.RemoveObserver(this);
+}
+
+void LeakDetectorController::OnLeakFound(
+    const LeakDetector::LeakReport& report) {

[Will Harris, 2016/02/18 04:49:45]

which threads are OnLeakFound and GetLeakReports being called on. Do you need a
thread checker here to avoid concurrent access to stored_reports_

[Simon Que, 2016/02/18 05:16:04]

OnLeakFound could be called from any thread but GetLeakReports will be called
from the main thread of the browser process, just like its counterpart
GetSampledProfiles() in perf_provider_chromeos.cc is currently being called.

Do you think a base::Lock() will suffice here?

+  stored_reports_.push_back(MemoryLeakReportProto());
+  MemoryLeakReportProto* proto = &stored_reports_.back();
+
+  // Copy the contents of the report to the protobuf.
+  proto->set_size_bytes(report.alloc_size_bytes);
+  proto->mutable_call_stack()->Reserve(report.call_stack.size());
+  for (uintptr_t call_stack_entry : report.call_stack)
+    proto->mutable_call_stack()->Add(call_stack_entry);
+
+  // Store the LeakDetector parameters in the protobuf.
+  proto->set_sampling_rate(kSamplingRate);
+  proto->set_max_stack_depth(kMaxStackDepth);
+  proto->set_analysis_interval_bytes(kAnalysisIntervalBytes);
+  proto->set_size_suspicion_threshold(kSizeSuspicionThreshold);
+  proto->set_call_stack_suspicion_threshold(kCallStackSuspicionThreshold);
+}
+
+void LeakDetectorController::GetLeakReports(
+    std::vector<MemoryLeakReportProto>* reports) {
+  *reports = std::move(stored_reports_);
+}
+
+}  // namespace metrics