components/metrics: Add runtime memory leak detector

components/metrics/leak_detector/leak_detector_value_type.h

Index: components/metrics/leak_detector/leak_detector_value_type.h
diff --git a/components/metrics/leak_detector/leak_detector_value_type.h b/components/metrics/leak_detector/leak_detector_value_type.h
new file mode 100644
index 0000000000000000000000000000000000000000..40f61081e9ae61b4dcd9b04a7ce41438062f0062
--- /dev/null
+++ b/components/metrics/leak_detector/leak_detector_value_type.h
@@ -0,0 +1,52 @@
+// 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_LEAK_DETECTOR_VALUE_TYPE_
+#define COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_VALUE_TYPE_
+
+#include <stddef.h>
+#include <stdint.h>
+
+namespace metrics {
+namespace leak_detector {
+
+// Used for tracking unique call stacks.
+// Not thread-safe.
+struct CallStack;
+
+class LeakDetectorValueType {
+ public:
+  // Supported types.
+  enum Type {
+    TYPE_NONE,
+    TYPE_SIZE,
+    TYPE_CALL_STACK,
+  };
+
+  LeakDetectorValueType() : type_(TYPE_NONE), size_(0), call_stack_(nullptr) {}
+  explicit LeakDetectorValueType(size_t size)
+      : type_(TYPE_SIZE), size_(size), call_stack_(nullptr) {}
+  explicit LeakDetectorValueType(const CallStack* call_stack)
+      : type_(TYPE_CALL_STACK), size_(0), call_stack_(call_stack) {}
+
+  // Accessors.
+  Type type() const { return type_; }
+  size_t size() const { return size_; }
+  const CallStack* call_stack() const { return call_stack_; }
+
+  // Comparators.
+  bool operator==(const LeakDetectorValueType& other) const;
+  bool operator<(const LeakDetectorValueType& other) const;
+
+ private:
+  Type type_;
+
+  size_t size_;
+  const CallStack* call_stack_;
+};
+
+}  // namespace leak_detector
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_VALUE_TYPE_