Revert of Delete SignalThread class.

webrtc/rtc_base/messagequeue.cc

Index: webrtc/rtc_base/messagequeue.cc
diff --git a/webrtc/rtc_base/messagequeue.cc b/webrtc/rtc_base/messagequeue.cc
index fac7609cbf23af709f53c7b061d626c4b0fd266b..883735c9cc771821248cc64f980a47523dc57316 100644
--- a/webrtc/rtc_base/messagequeue.cc
+++ b/webrtc/rtc_base/messagequeue.cc
@@ -43,16 +43,6 @@ class SCOPED_LOCKABLE MarkProcessingCritScope {
 
   RTC_DISALLOW_COPY_AND_ASSIGN(MarkProcessingCritScope);
 };
-
-class FunctorPostMessageHandler : public MessageHandler {
- public:
-  void OnMessage(Message* msg) override {
-    RunnableData* data = static_cast<RunnableData*>(msg->pdata);
-    data->Run();
-    delete data;
-  }
-};
-
 }  // namespace
 
 //------------------------------------------------------------------
@@ -546,12 +536,4 @@ void MessageQueue::Dispatch(Message *pmsg) {
   }
 }
 
-void MessageQueue::PostFunctorInternal(const Location& posted_from,
-                                       RunnableData* message_data) {
-  // Use static to ensure it outlives this scope. Safe since
-  // FunctorPostMessageHandler keeps no state.
-  static FunctorPostMessageHandler handler;
-  Post(posted_from, &handler, 0, message_data);
-}
-
 }  // namespace rtc