WARN_UNUSED_RESULT on all Thread/SequenceChecker impls

base/sequence_checker.h

 // Copyright (c) 2012 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_CHECKER_H_
 #define BASE_SEQUENCE_CHECKER_H_
 
+#include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/sequence_checker_impl.h"
 
 // SequenceChecker is a helper class used to help verify that some methods of a
 // class are called sequentially (for thread-safety).
 //
 // Use the macros below instead of the SequenceChecker directly so that the
 // unused member doesn't result in an extra byte (four when padded) per
 // instance in production.
 //
@@ skipping 41 matching lines @@
 #endif  // DCHECK_IS_ON()
 
 namespace base {
 
 // Do nothing implementation, for use in release mode.
 //
 // Note: You should almost always use the SequenceChecker class (through the
 // above macros) to get the right version for your build configuration.
 class SequenceCheckerDoNothing {
  public:
-  bool CalledOnValidSequence() const { return true; }
+  bool CalledOnValidSequence() const WARN_UNUSED_RESULT { return true; }
 
   void DetachFromSequence() {}
 };
 
 #if DCHECK_IS_ON()
 class SequenceChecker : public SequenceCheckerImpl {
 };
 #else
 class SequenceChecker : public SequenceCheckerDoNothing {
 };
 #endif  // DCHECK_IS_ON()
 
 }  // namespace base
 
 #endif  // BASE_SEQUENCE_CHECKER_H_