Implement a simple ThreadChecker for Mojo and add to |internal::SharedData| and |internal::Router|.

third_party/mojo/src/mojo/public/cpp/bindings/lib/thread_checker.h

+// Copyright 2015 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 MOJO_PUBLIC_CPP_BINDINGS_LIB_THREAD_CHECKER_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_LIB_THREAD_CHECKER_H_
+
+#include "mojo/public/cpp/system/macros.h"
+
+#if !defined(_WIN32)
+#include "mojo/public/cpp/bindings/lib/thread_checker_posix.h"
+#endif
+
+namespace mojo {
+namespace internal {
+
+class ThreadCheckerDoNothing {
+ public:
+  bool CalledOnValidThread() const MOJO_WARN_UNUSED_RESULT {
+    return true;
+  }
+};
+
+// ThreadChecker is a class used to verify that some methods of a class are
+// called from the same thread. It is meant to be a member variable of a class.
+// The entire lifecycle of a ThreadChecker must occur on a single thread.
+// In Release mode (without dcheck_always_on), ThreadChecker does nothing.
+#if !defined(_WIN32) && (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+using ThreadChecker = ThreadCheckerPosix;
+#else
+using ThreadChecker = ThreadCheckerDoNothing;
+#endif
+
+}  // namespace internal
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_THREAD_CHECKER_H_