Revert of components/metrics: Add runtime memory leak detector

components/metrics/leak_detector/call_stack_manager.h

-// 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_CALL_STACK_MANAGER_H_
-#define COMPONENTS_METRICS_LEAK_DETECTOR_CALL_STACK_MANAGER_H_
-
-#include <stdint.h>
-
-#include "base/containers/hash_tables.h"
-#include "base/macros.h"
-#include "components/metrics/leak_detector/custom_allocator.h"
-#include "components/metrics/leak_detector/stl_allocator.h"
-
-// Summary of structures:
-//
-// struct CallStack:
-//   Represents a unique call stack, defined by its raw call stack (array of
-//   pointers), and hash value. All CallStack objects are owned by class
-//   CallStackManager. Other classes may hold pointers to them but should not
-//   attempt to create or modify any CallStack objects.
-//
-// class CallStackManager:
-//   Creates CallStack objects to represent unique call stacks. Owns all
-//   CallStack objects that it creates, storing them internally.
-//
-//   Returns the call stacks as const pointers because no caller should take
-//   ownership of them and modify or delete them. The lifetime of all CallStack
-//   objects is limited to that of the CallStackManager object that created
-//   them. When the CallStackManager is destroyed, the CallStack objects will be
-//   invalidated. Hence the caller should make sure that it does not use
-//   CallStack objects beyond the lifetime of the CallStackManager that created
-//   them.
-
-namespace metrics {
-namespace leak_detector {
-
-// Struct to represent a call stack.
-struct CallStack {
-  // Call stack as an array of pointers, |stack|. The array length is stored in
-  // |depth|. There is no null terminator.
-  const void** stack;
-  size_t depth;
-
-  // Hash of call stack. It is cached here so that it doesn not have to be
-  // recomputed each time.
-  size_t hash;
-};
-
-// Maintains and owns all unique call stack objects.
-// Not thread-safe.
-class CallStackManager {
- public:
-  CallStackManager();
-  ~CallStackManager();
-
-  // Returns a CallStack object for a given raw call stack. The first time a
-  // particular raw call stack is passed into this function, it will create a
-  // new CallStack object to hold the raw call stack data, and then return it.
-  // The CallStack object is stored internally.
-  //
-  // On subsequent calls with the same raw call stack, this function will return
-  // the previously created CallStack object.
-  const CallStack* GetCallStack(size_t depth, const void* const stack[]);
-
-  size_t size() const { return call_stacks_.size(); }
-
- private:
-  // Allocator class for unique call stacks.
-  using CallStackPointerAllocator = STLAllocator<CallStack*, CustomAllocator>;
-
-  // Hash operator for call stack object given as a pointer.
-  // Does not actually compute the hash. Instead, returns the already computed
-  // hash value stored in a CallStack object.
-  struct CallStackPointerStoredHash {
-    size_t operator()(const CallStack* call_stack) const {
-      return call_stack->hash;
-    }
-  };
-
-  // Equality comparator for call stack objects given as pointers. Compares
-  // their stack trace contents.
-  struct CallStackPointerEqual {
-    bool operator()(const CallStack* c1, const CallStack* c2) const;
-  };
-
-  // Holds all call stack objects. Each object is allocated elsewhere and stored
-  // as a pointer because the container may rearrange itself internally.
-  base::hash_set<CallStack*,
-                 CallStackPointerStoredHash,
-                 CallStackPointerEqual,
-                 CallStackPointerAllocator> call_stacks_;
-
-  DISALLOW_COPY_AND_ASSIGN(CallStackManager);
-};
-
-}  // namespace leak_detector
-}  // namespace metrics
-
-#endif  // COMPONENTS_METRICS_LEAK_DETECTOR_CALL_STACK_MANAGER_H_