Don't rely on undefined macro behaviour in unit tests.

base/threading/thread_checker_unittest.cc

 // 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.
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/threading/simple_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 // Duplicated from base/threading/thread_checker.h so that we can be
 // good citizens there and undef the macro.
-#define ENABLE_THREAD_CHECKER (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))

[jar (doing other things), 2012/06/26 23:02:40]

nit: You don't need the outer parens

+#define ENABLE_THREAD_CHECKER 1
+#else
+#define ENABLE_THREAD_CHECKER 0
+#endif
 
 namespace base {
 
 // Simple class to exercise the basics of ThreadChecker.
 // Both the destructor and DoStuff should verify that they were
 // called on the same thread as the constructor.
 class ThreadCheckerClass : public ThreadChecker {
  public:
   ThreadCheckerClass() {}
 
@@ skipping 140 matching lines @@
   ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl();
 }
 #endif  // ENABLE_THREAD_CHECKER
 
 #endif  // GTEST_HAS_DEATH_TEST || !ENABLE_THREAD_CHECKER
 
 // Just in case we ever get lumped together with other compilation units.
 #undef ENABLE_THREAD_CHECKER
 
 }  // namespace base