Adding the ability to use a simulated clock for unit tests.

webrtc/base/messagequeue.cc

Index: webrtc/base/messagequeue.cc
diff --git a/webrtc/base/messagequeue.cc b/webrtc/base/messagequeue.cc
index 61aa61192bbad69d87ddf5e79aab3a5af3ce290f..140dd672244e9210efac0ca07bf6bd4cc27afde5 100644
--- a/webrtc/base/messagequeue.cc
+++ b/webrtc/base/messagequeue.cc
@@ -113,6 +113,27 @@ void MessageQueueManager::ClearInternal(MessageHandler *handler) {
     (*iter)->Clear(handler);
 }
 
+class NoOpMessageHandler : public MessageHandler {
+ public:
+  void OnMessage(Message* msg) override {}
+};
+
+void MessageQueueManager::WakeAllMessageQueues() {
+  if (!instance_) {
+    return;
+  }
+  return Instance()->WakeAllMessageQueuesInternal();
+}
+void MessageQueueManager::WakeAllMessageQueuesInternal() {
+#if CS_DEBUG_CHECKS  // CurrentThreadIsOwner returns true by default.
+  ASSERT(!crit_.CurrentThreadIsOwner());  // See note above.
+#endif
+  CritScope cs(&crit_);
+  for (MessageQueue* queue : message_queues_) {
+    queue->Post(new NoOpMessageHandler(), 0);
+  }
+}
+
 //------------------------------------------------------------------
 // MessageQueue