(3) Rename files to snake_case: move the files

Mechanically generated with this command:

tools_webrtc/do-rename.sh move all-renames.txt

Bug: webrtc:10159
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I8b05b6eab9b9d18b29c2199bbea239e9add1e690
Reviewed-on: https://webrtc-review.googlesource.com/c/115481
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26225}

rtc_base/message_handler.h

@@ -0,0 +1,70 @@
+/*
+ *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef RTC_BASE_MESSAGEHANDLER_H_
+#define RTC_BASE_MESSAGEHANDLER_H_
+
+#include <utility>
+
+#include "rtc_base/constructormagic.h"
+
+namespace rtc {
+
+struct Message;
+
+// Messages get dispatched to a MessageHandler
+
+class MessageHandler {
+ public:
+  virtual ~MessageHandler();
+  virtual void OnMessage(Message* msg) = 0;
+
+ protected:
+  MessageHandler() {}
+
+ private:
+  RTC_DISALLOW_COPY_AND_ASSIGN(MessageHandler);
+};
+
+// Helper class to facilitate executing a functor on a thread.
+template <class ReturnT, class FunctorT>
+class FunctorMessageHandler : public MessageHandler {
+ public:
+  explicit FunctorMessageHandler(FunctorT&& functor)
+      : functor_(std::forward<FunctorT>(functor)) {}
+  virtual void OnMessage(Message* msg) { result_ = functor_(); }
+  const ReturnT& result() const { return result_; }
+
+  // Returns moved result. Should not call result() or MoveResult() again
+  // after this.
+  ReturnT MoveResult() { return std::move(result_); }
+
+ private:
+  FunctorT functor_;
+  ReturnT result_;
+};
+
+// Specialization for ReturnT of void.
+template <class FunctorT>
+class FunctorMessageHandler<void, FunctorT> : public MessageHandler {
+ public:
+  explicit FunctorMessageHandler(FunctorT&& functor)
+      : functor_(std::forward<FunctorT>(functor)) {}
+  virtual void OnMessage(Message* msg) { functor_(); }
+  void result() const {}
+  void MoveResult() {}
+
+ private:
+  FunctorT functor_;
+};
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_MESSAGEHANDLER_H_