components/metrics: Add runtime memory leak detector

components/metrics/leak_detector/stl_allocator.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 COMPONENTS_METRICS_LEAK_DETECTOR_STL_ALLOCATOR_H_
+#define COMPONENTS_METRICS_LEAK_DETECTOR_STL_ALLOCATOR_H_
+
+#include <stddef.h>
+
+#include <limits>
+#include <memory>
+
+#include "base/logging.h"
+
+// Generic allocator class for STL objects.
+// deallocate() to use the template class Alloc's allocation.
+// that uses a given type-less allocator Alloc, which must provide:
+//   static void* Alloc::Allocate(size_t size);
+//   static void Alloc::Free(void* ptr, size_t size);
+//
+// Inherits from the default allocator, std::allocator. Overrides allocate() and
+// deallocate() and some other functions.
+//
+// STLAllocator<T, MyAlloc> provides the same thread-safety guarantees as
+// MyAlloc.
+//
+// Usage example:
+//   set<T, less<T>, STLAllocator<T, MyAlloc> > my_set;
+
+template <typename T, class Alloc>
+class STLAllocator : public std::allocator<T> {
+ public:
+  typedef size_t     size_type;
+  typedef T*         pointer;
+
+  template <class T1> struct rebind {
+    typedef STLAllocator<T1, Alloc> other;
+  };
+
+  STLAllocator() {}
+  explicit STLAllocator(const STLAllocator&) {}
+  template <class T1> STLAllocator(const STLAllocator<T1, Alloc>&) {}
+  ~STLAllocator() {}
+
+  pointer allocate(size_type n, const void* = 0) {
+    // Make sure the computation of the total allocation size does not cause an
+    // integer overflow.
+    RAW_CHECK(n < max_size());
+    return static_cast<T*>(Alloc::Allocate(n * sizeof(T)));
+  }
+
+  void deallocate(pointer p, size_type n) {
+    Alloc::Free(p, n * sizeof(T));
+  }
+
+  size_type max_size() const {
+    return std::numeric_limits<size_t>::max() / sizeof(T);
+  }
+};
+
+#endif  // COMPONENTS_METRICS_LEAK_DETECTOR_STL_ALLOCATOR_H_