Make ThreadChecker::CalledOnValidThread() return true when called from the same task.

base/sequence_token.h

-// Copyright 2016 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_SEQUENCE_TOKEN_H_
-#define BASE_SEQUENCE_TOKEN_H_
-
-#include "base/base_export.h"
-#include "base/macros.h"
-
-namespace base {
-
-// A token that identifies a series of sequenced tasks (i.e. tasks that run one
-// at a time in posting order).
-class BASE_EXPORT SequenceToken {
- public:
-  // Instantiates an invalid SequenceToken.
-  SequenceToken() = default;
-
-  // Explicitly allow copy.
-  SequenceToken(const SequenceToken& other) = default;
-  SequenceToken& operator=(const SequenceToken& other) = default;
-
-  // An invalid SequenceToken is not equal to any other SequenceToken, including
-  // other invalid SequenceTokens.
-  bool operator==(const SequenceToken& other) const;
-  bool operator!=(const SequenceToken& other) const;
-
-  // Returns true if this is a valid SequenceToken.
-  bool IsValid() const;
-
-  // Returns a valid SequenceToken which isn't equal to any previously returned
-  // SequenceToken.
-  static SequenceToken Create();
-
-  // Returns the SequenceToken associated with the task running on the current
-  // thread, as determined by the active ScopedSetSequenceTokenForCurrentThread
-  // if any.
-  static SequenceToken GetForCurrentThread();
-
- private:
-  SequenceToken(int token) : token_(token) {}
-
-  static constexpr int kInvalidSequenceToken = -1;
-  int token_ = kInvalidSequenceToken;
-};
-
-// Throughout its lifetime, determines the value returned by
-// SequenceToken::GetForCurrentThread().
-class BASE_EXPORT ScopedSetSequenceTokenForCurrentThread {
- public:
-  ScopedSetSequenceTokenForCurrentThread(const SequenceToken& token);
-  ~ScopedSetSequenceTokenForCurrentThread();
-
- private:
-  friend class SequenceToken;
-
-  const SequenceToken token_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedSetSequenceTokenForCurrentThread);
-};
-
-}  // namespace base
-
-#endif  // BASE_SEQUENCE_TOKEN_H_