libchrome: Uprev the library to r456626 from Chromium

Pulled the latest and greatest version of libchrome from Chromium.

The merge was done against r456626 which corresponds to git commit
08266b3fca707804065a2cfd60331722ade41969 of Mar 14, 2017

Notable changes are:
- FOR_EACH_OBSERVER macro removed (replaced by use of C++ 11
  range-base for loop)
- base::Values no more FundamentalValue
- stl_util moved to base namespace
- some scoped pointers removed in crypto/ in favor
  of BoringSSL UniquePtr.
- path() accessor renamed to GetPath() in ScopedTempDir (and other
  classes)
- introduction of base::CallbackOnce

Test: All unit-tests should still pass.

Change-Id: I5c2cb41ea4c037fe69fbb425e711b1399d55d591

1 files changed, 115 insertions, 0 deletions

diff --git a/base/sequence_token.h b/base/sequence_token.h
new file mode 100644
index 0000000000..6e7d191ae8
--- /dev/null
+++ b/base/sequence_token.h
@@ -0,0 +1,115 @@
+// 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 the integer uniquely representing this SequenceToken. This method
+  // should only be used for tracing and debugging.
+  int ToInternalValue() 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:
+  explicit SequenceToken(int token) : token_(token) {}
+
+  static constexpr int kInvalidSequenceToken = -1;
+  int token_ = kInvalidSequenceToken;
+};
+
+// A token that identifies a task.
+//
+// This is used by ThreadCheckerImpl to determine whether calls to
+// CalledOnValidThread() come from the same task and hence are deterministically
+// single-threaded (vs. calls coming from different sequenced or parallel tasks,
+// which may or may not run on the same thread).
+class BASE_EXPORT TaskToken {
+ public:
+  // Instantiates an invalid TaskToken.
+  TaskToken() = default;
+
+  // Explicitly allow copy.
+  TaskToken(const TaskToken& other) = default;
+  TaskToken& operator=(const TaskToken& other) = default;
+
+  // An invalid TaskToken is not equal to any other TaskToken, including
+  // other invalid TaskTokens.
+  bool operator==(const TaskToken& other) const;
+  bool operator!=(const TaskToken& other) const;
+
+  // Returns true if this is a valid TaskToken.
+  bool IsValid() const;
+
+  // In the scope of a ScopedSetSequenceTokenForCurrentThread, returns a valid
+  // TaskToken which isn't equal to any TaskToken returned in the scope of a
+  // different ScopedSetSequenceTokenForCurrentThread. Otherwise, returns an
+  // invalid TaskToken.
+  static TaskToken GetForCurrentThread();
+
+ private:
+  friend class ScopedSetSequenceTokenForCurrentThread;
+
+  explicit TaskToken(int token) : token_(token) {}
+
+  // Returns a valid TaskToken which isn't equal to any previously returned
+  // TaskToken. This is private as it only meant to be instantiated by
+  // ScopedSetSequenceTokenForCurrentThread.
+  static TaskToken Create();
+
+  static constexpr int kInvalidTaskToken = -1;
+  int token_ = kInvalidTaskToken;
+};
+
+// Instantiate this in the scope where a single task runs.
+class BASE_EXPORT ScopedSetSequenceTokenForCurrentThread {
+ public:
+  // Throughout the lifetime of the constructed object,
+  // SequenceToken::GetForCurrentThread() will return |sequence_token| and
+  // TaskToken::GetForCurrentThread() will return a TaskToken which is not equal
+  // to any TaskToken returned in the scope of another
+  // ScopedSetSequenceTokenForCurrentThread.
+  ScopedSetSequenceTokenForCurrentThread(const SequenceToken& sequence_token);
+  ~ScopedSetSequenceTokenForCurrentThread();
+
+ private:
+  const SequenceToken sequence_token_;
+  const TaskToken task_token_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedSetSequenceTokenForCurrentThread);
+};
+
+}  // namespace base
+
+#endif  // BASE_SEQUENCE_TOKEN_H_