Remove usage of FOR_EACH_OBSERVER macro in remoting

remoting/signaling/delegating_signal_strategy.cc

Index: remoting/signaling/delegating_signal_strategy.cc
diff --git a/remoting/signaling/delegating_signal_strategy.cc b/remoting/signaling/delegating_signal_strategy.cc
index d1a374adf6f36fa86449a4b8ff748917200bd246..693eab38b49885540b3a7853b015d967c47ee8fa 100644
--- a/remoting/signaling/delegating_signal_strategy.cc
+++ b/remoting/signaling/delegating_signal_strategy.cc
@@ -46,8 +46,8 @@ void DelegatingSignalStrategy::OnIncomingMessage(const std::string& message) {
 
 void DelegatingSignalStrategy::Connect() {
   DCHECK(client_task_runner_->BelongsToCurrentThread());
-  FOR_EACH_OBSERVER(Listener, listeners_,
-                    OnSignalStrategyStateChange(CONNECTED));
+  for (auto& observer : listeners_)
+    observer.OnSignalStrategyStateChange(CONNECTED);
 }
 
 void DelegatingSignalStrategy::Disconnect() {