Update from https://crrev.com/327068

base/trace_event/memory_allocator_attributes_type_info.h

Index: base/trace_event/memory_allocator_attributes_type_info.h
diff --git a/base/trace_event/memory_allocator_attributes_type_info.h b/base/trace_event/memory_allocator_attributes_type_info.h
new file mode 100644
index 0000000000000000000000000000000000000000..c3986ae2e8eda9326b97a88c28d50fd86df62314
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+++ b/base/trace_event/memory_allocator_attributes_type_info.h
@@ -0,0 +1,49 @@
+// 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 BASE_TRACE_EVENT_MEMORY_ALLOCATOR_ATTRIBUTES_TYPE_INFO_H_
+#define BASE_TRACE_EVENT_MEMORY_ALLOCATOR_ATTRIBUTES_TYPE_INFO_H_
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/containers/hash_tables.h"
+
+namespace base {
+namespace trace_event {
+
+// A dictionary of "allocator_name/attribute_name" -> "attribute_type" which
+// supports merging and enforces duplicate checking.
+class BASE_EXPORT MemoryAllocatorAttributesTypeInfo {
+ public:
+  MemoryAllocatorAttributesTypeInfo();
+  ~MemoryAllocatorAttributesTypeInfo();
+
+  // Returns the attribute type, or an empty string if not found.
+  const std::string& Get(const std::string& allocator_name,
+                         const std::string& attribute_name) const;
+
+  // Refer to tools/perf/unit-info.json for the semantics of |attribute_type|.
+  void Set(const std::string& allocator_name,
+           const std::string& attribute_name,
+           const std::string& attribute_type);
+
+  // Checks whether a given {allocator_name, attribute_name} declaration exists.
+  bool Exists(const std::string& allocator_name,
+              const std::string& attribute_name) const;
+
+  // Merges the attribute types declared in |other| into this.
+  void Update(const MemoryAllocatorAttributesTypeInfo& other);
+
+ private:
+  // "allocator_name/attribute_name" -> attribute_type.
+  hash_map<std::string, std::string> type_info_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryAllocatorAttributesTypeInfo);
+};
+
+}  // namespace trace_event
+}  // namespace base
+
+#endif  // BASE_TRACE_EVENT_MEMORY_ALLOCATOR_ATTRIBUTES_TYPE_INFO_H_