Make ThreadChecker zero-sized

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 <memory>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequence_token.h"
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/simple_thread.h"
+#include "base/threading/thread_checker.h"
 #include "base/threading/thread_checker_impl.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 namespace {
 
+#if !DCHECK_IS_ON()
+class ClassWithThreadChecker {
+  BASE_EXPORT size_t SilenceUnusedWarnings() {
+    return x + (y.CalledOnValidThread() ? 1 : 0);
+  }
+  uint32_t x;
+  ThreadChecker y;
+};
+
+static_assert(sizeof(ClassWithThreadChecker) == sizeof(uint32_t), "ThreadCheckerShouldHaveZeroSize");
+#endif
+
 // A thread that runs a callback.
 class RunCallbackThread : public SimpleThread {
  public:
   explicit RunCallbackThread(const Closure& callback)
       : SimpleThread("RunCallbackThread"), callback_(callback) {}
 
  private:
   // SimpleThread:
   void Run() override { callback_.Run(); }
 
@@ skipping 155 matching lines @@
 
   // Verify that CalledOnValidThread() returns true when called on a different
   // thread after a call to DetachFromThread().
   RunCallbackOnNewThreadSynchronously(
       Bind(&ExpectCalledOnValidThread, Unretained(&thread_checker)));
 
   EXPECT_FALSE(thread_checker.CalledOnValidThread());
 }
 
 }  // namespace base