Move files in wtf/ to platform/wtf/ (Part 9).

third_party/WebKit/Source/wtf/text/AtomicStringHash.h

-/*
- * Copyright (C) 2008 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1.  Redistributions of source code must retain the above copyright
- *     notice, this list of conditions and the following disclaimer.
- * 2.  Redistributions in binary form must reproduce the above copyright
- *     notice, this list of conditions and the following disclaimer in the
- *     documentation and/or other materials provided with the distribution.
- * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
- *     its contributors may be used to endorse or promote products derived
- *     from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
+// 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 AtomicStringHash_h
-#define AtomicStringHash_h
+#include "platform/wtf/text/AtomicStringHash.h"
 
-#include "wtf/HashTraits.h"
-#include "wtf/text/AtomicString.h"
-
-namespace WTF {
-
-struct AtomicStringHash {
-  static unsigned hash(const AtomicString& key) {
-    return key.impl()->existingHash();
-  }
-
-  static bool equal(const AtomicString& a, const AtomicString& b) {
-    return a == b;
-  }
-
-  static const bool safeToCompareToEmptyOrDeleted = false;
-};
-
-// AtomicStringHash is the default hash for AtomicString
-template <>
-struct HashTraits<AtomicString> : SimpleClassHashTraits<AtomicString> {
-  // Unlike other types, we can return a const reference for AtomicString's
-  // empty value (nullAtom).
-  typedef const AtomicString& PeekOutType;
-
-  static const AtomicString& emptyValue() { return nullAtom; }
-  static PeekOutType peek(const AtomicString& value) { return value; }
-
-  static const bool hasIsEmptyValueFunction = true;
-  static bool isEmptyValue(const AtomicString& value) { return value.isNull(); }
-};
-
-}  // namespace WTF
-
-using WTF::AtomicStringHash;
-
-#endif
+// The contents of this header was moved to platform/wtf as part of
+// WTF migration project. See the following post for details:
+// https://groups.google.com/a/chromium.org/d/msg/blink-dev/tLdAZCTlcAA/bYXVT8gYCAAJ