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..9ced11df8320f048a96939c2e23ec0d99463f461
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+++ b/components/metrics/leak_detector/leak_detector_value_type.h
@@ -0,0 +1,70 @@
+// 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 leak_detector {
+
+// Used for tracking unique call stacks.
+class CallStack;
+
+class LeakDetectorValueType {
+ public:
+  // Supported types.
+  enum Type {
+    kNone,
+    kSize,
+    kCallStack,
+  };
+
+  LeakDetectorValueType()
+      : type_(kNone),
+        size_(0),
+        call_stack_(nullptr) {}
+  explicit LeakDetectorValueType(uint32_t size)
+      : type_(kSize),
+        size_(size),
+        call_stack_(nullptr) {}
+  explicit LeakDetectorValueType(const CallStack* call_stack)
+      : type_(kCallStack),
+        size_(0),
+        call_stack_(call_stack) {}
+
+  // Accessors.
+  Type type() const {
+    return type_;
+  }
+  uint32_t size() const {
+    return size_;
+  }
+  const CallStack* call_stack() const {
+    return call_stack_;
+  }
+
+  // Returns a string containing the word that describes the value type of the
+  // current object. e.g. "size" or "call stack".
+  const char* GetTypeName() const;
+
+  // Writes the current value as a string to |buffer|. Will not write beyond the
+  // buffer size given by |buffer_size|. Returns |buffer| as a const ptr.
+  const char* ToString(size_t buffer_size, char* buffer) const;
+
+  // Comparators.
+  bool operator== (const LeakDetectorValueType& other) const;
+  bool operator< (const LeakDetectorValueType& other) const;
+
+ private:
+  Type type_;
+
+  uint32_t size_;
+  const CallStack* call_stack_;
+};
+
+}  // namespace leak_detector
+
+#endif  // COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_VALUE_TYPE_