components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/gperftools/spin_lock_wrapper.h

+// 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.
+
+#ifndef SPINLOCK_WRAPPER_H_
+#define SPINLOCK_WRAPPER_H_
+
+class SpinLock;
+
+// A container class for using tcmalloc's SpinLock class.
+// This avoids users of this class to directly include those classes, causing

[jar (doing other things), 2015/08/21 02:48:43]

nit: typos in sentence.  I don't know what you meant to write.

[Simon Que, 2015/08/21 21:59:20]

Done.

+// #include path conflicts.
+
+// SpinLockWrapper depends on CustomAllocator, which must be initialized before
+// any instance of this class is created.
+class SpinLockWrapper {
+ public:
+  SpinLockWrapper();
+  ~SpinLockWrapper();
+
+  void Lock();
+  void Unlock();
+
+ private:
+  SpinLock* lock_;
+};
+
+// Corresponding locker object that arranges to acquire a spinlock for the
+// duration of a C++ scope.
+class ScopedSpinLockHolder {
+ public:
+  explicit ScopedSpinLockHolder(SpinLockWrapper* lock) : lock_(lock) {
+    lock_->Lock();
+  }
+
+  ~ScopedSpinLockHolder() {
+    lock_->Unlock();
+  }
+
+ private:
+  SpinLockWrapper* lock_;
+};
+
+#endif  // SPINLOCK_WRAPPER_H_