components/metrics: Add runtime memory leak detector

components/metrics/leak_detector/ranked_list.cc

Index: components/metrics/leak_detector/ranked_list.cc
diff --git a/components/metrics/leak_detector/ranked_list.cc b/components/metrics/leak_detector/ranked_list.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4900025cf3cb6b7180612f6195714c692cca07b9
--- /dev/null
+++ b/components/metrics/leak_detector/ranked_list.cc
@@ -0,0 +1,45 @@
+// Copyright 2015 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/ranked_list.h"
+
+#include <algorithm>
+
+namespace metrics {
+namespace leak_detector {
+
+RankedList::RankedList(size_t max_size) : max_size_(max_size) {}
+
+RankedList::~RankedList() {}
+
+RankedList::RankedList(RankedList::RValue other)
+    : max_size_(other.object->max_size_) {
+  entries_.swap(other.object->entries_);
+}
+
+RankedList& RankedList::operator=(RankedList::RValue other) {
+  max_size_ = other.object->max_size_;
+  entries_.swap(other.object->entries_);
+  return *this;
+}
+
+void RankedList::Add(const ValueType& value, int count) {
+  // Determine where to insert the value given its count.
+  EntryList::iterator iter = std::upper_bound(entries_.begin(), entries_.end(),
+                                              Entry{ValueType(), count});
+
+  // If the list is full, do not add any entry with |count| if does not exceed
+  // the lowest count of the entries in the list.
+  if (size() == max_size_ && iter == end())
+    return;
+
+  entries_.insert(iter, Entry({value, count}));
+
+  // Limit the list size if it exceeds the maximum allowed size.
+  if (entries_.size() > max_size_)
+    entries_.resize(max_size_);
+}
+
+}  // namespace leak_detector
+}  // namespace metrics