Add out-of-process memory logging stream parsing.

chrome/profiling/allocation_tracker.h

+// Copyright 2017 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 CHROME_PROFILING_ALLOCATION_TRACKER_H_
+#define CHROME_PROFILING_ALLOCATION_TRACKER_H_
+
+#include <map>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "chrome/profiling/memlog_receiver.h"
+#include "chrome/profiling/stack_storage.h"
+
+namespace profiling {
+
+// Tracks live allocations in one process.

[awong, 2017/06/19 20:00:13]

Can you add a TODO() comment staying this is an analogue to the memory-infra
allocation register and the two need to be merged/deduped?

+class AllocationTracker : public MemlogReceiver {
+ public:
+  using CompleteCallback = base::OnceClosure;
+
+  explicit AllocationTracker(CompleteCallback complete_cb);
+  ~AllocationTracker() override;
+
+  void OnHeader(const StreamHeader& header) override;
+  void OnAlloc(const AllocPacket& alloc_packet, Stack&& stack) override;
+  void OnFree(const FreePacket& free_packet) override;
+  void OnComplete() override;
+
+ private:
+  CompleteCallback complete_callback_;
+
+  struct Alloc {
+    Alloc(size_t sz, StackStorage::Key key);
+
+    size_t size;
+    StackStorage::Key stack_key;
+  };
+
+  // Cached pointer to the global singleton.
+  StackStorage* stack_storage_;
+
+  std::map<Address, Alloc> live_allocs_;
+
+  DISALLOW_COPY_AND_ASSIGN(AllocationTracker);
+};
+
+}  // namespace profiling
+
+#endif  // CHROME_PROFILING_ALLOCATION_TRACKER_H_