Revert "Move files in wtf/ to platform/wtf/"

third_party/WebKit/Source/wtf/debug/CrashLogging.h

-// Copyright 2017 The Chromium Authors. All rights reserved.
+// 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.
 
-#include "platform/wtf/debug/CrashLogging.h"
+#ifndef WTF_CrashLogging_h
+#define WTF_CrashLogging_h
 
-// 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
+#include "base/debug/crash_logging.h"
+#include "wtf/WTFExport.h"
+
+namespace WTF {
+namespace debug {
+
+using ScopedCrashKey = base::debug::ScopedCrashKey;
+
+}  // namespace debug
+}  // namespace WTF
+
+#endif  // WTF_CrashLogging_h