Locking for Notification class.

include/gtest/internal/gtest-port.h

@@ -1102,22 +1102,37 @@ inline void SleepMilliseconds(int n) {
 // use it in user tests, either directly or indirectly.
 class Notification {
  public:
-  Notification() : notified_(false) {}
+  Notification() : notified_(false) {
+    GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_init(&mutex_, NULL));
+  }
+  ~Notification() {
+    pthread_mutex_destroy(&mutex_);
+  }
 
   // Notifies all threads created with this notification to start. Must
   // be called from the controller thread.
-  void Notify() { notified_ = true; }
+  void Notify() {
+    pthread_mutex_lock(&mutex_);
+    notified_ = true;
+    pthread_mutex_unlock(&mutex_);
+  }
 
   // Blocks until the controller thread notifies. Must be called from a test
   // thread.
   void WaitForNotification() {
-    while (!notified_) {
+    for (;;) {
+      pthread_mutex_lock(&mutex_);
+      const bool notified = notified_;
+      pthread_mutex_unlock(&mutex_);
+      if (notified)
+        break;
       SleepMilliseconds(10);
     }
   }
 
  private:
-  volatile bool notified_;
+  pthread_mutex_t mutex_;
+  bool notified_;
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(Notification);
 };