Add out-of-process memory logging stream parsing.

chrome/profiling/stack_storage.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_STACK_STORAGE_H_
+#define CHROME_PROFILING_STACK_STORAGE_H_
+
+#include <unordered_set>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "chrome/profiling/stack.h"
+
+namespace profiling {
+
+// This class is threadsafe.
+class StackStorage {
+ public:
+  using Container = std::unordered_set<Stack>;
+  using Key = Container::iterator;
+
+  StackStorage();
+  ~StackStorage();
+
+  // Adds the give stack to the storage and returns a key to it. If a matching
+  // stack already exists, a key to the existing one will be returned.
+  //
+  // The returned key will have a reference count associated with it, call
+  // Free when the key is no longer needed.
+  Key Insert(Stack&& stack);
+
+  // Frees one reference to a stack.
+  void Free(const Key& key);
+  void Free(const std::vector<Key>& keys);
+
+  // Returns the stack associated with the given key. Assumes the caller holds
+  // a key to it that will keep the stack in scope.
+  const Stack& GetStackForKey(const Key& key) const;
+
+ private:
+  mutable base::Lock lock_;
+
+  // List of live stacks for de-duping. Protected by the lock_.
+  Container stacks_;
+};
+
+}  // namespace profiling
+
+#endif  // CHROME_PROFILING_STACK_STORAGE_H_