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_posix.cc

Index: third_party/mojo/src/mojo/public/cpp/bindings/lib/thread_checker_posix.cc
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/thread_checker_posix.cc b/third_party/mojo/src/mojo/public/cpp/bindings/lib/thread_checker_posix.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c8a16e24655952f8c786cf2b1337a422e178cb2b
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/thread_checker_posix.cc
@@ -0,0 +1,24 @@
+// 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.
+
+#include "mojo/public/cpp/bindings/lib/thread_checker_posix.h"
+
+#include <assert.h>
+
+namespace mojo {
+namespace internal {
+
+ThreadCheckerPosix::ThreadCheckerPosix() : attached_thread_id_(pthread_self()) {
+}
+
+ThreadCheckerPosix::~ThreadCheckerPosix() {
+  assert(CalledOnValidThread());
+}
+
+bool ThreadCheckerPosix::CalledOnValidThread() const {
+  return pthread_equal(pthread_self(), attached_thread_id_);
+}
+
+}  // namespace internal
+}  // namespace mojo