Revert of Remove remains of webrtc/base (patchset #7 id:120001 of https://codereview.webrtc.org/297…

webrtc/base/thread_annotations.h

Index: webrtc/base/thread_annotations.h
diff --git a/webrtc/base/thread_annotations.h b/webrtc/base/thread_annotations.h
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+//
+// Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the LICENSE file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS.  All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+//
+// Borrowed from
+// https://code.google.com/p/gperftools/source/browse/src/base/thread_annotations.h
+// but adapted for clang attributes instead of the gcc.
+//
+// This header file contains the macro definitions for thread safety
+// annotations that allow the developers to document the locking policies
+// of their multi-threaded code. The annotations can also help program
+// analysis tools to identify potential thread safety issues.
+
+#ifndef WEBRTC_BASE_THREAD_ANNOTATIONS_H_
+#define WEBRTC_BASE_THREAD_ANNOTATIONS_H_
+
+
+// This header is deprecated and is just left here temporarily during
+// refactoring. See https://bugs.webrtc.org/7634 for more details.
+#include "webrtc/rtc_base/thread_annotations.h"
+
+#endif  // WEBRTC_BASE_THREAD_ANNOTATIONS_H_