Revert "Split EventWrapper in twain."

This reverts commit 9509fbfc301dd5412804ce5731afedc81480f2f8.

This is to debug a Chromium issue that WebRTC hangs if there is > 1 PeerConnection active in the browser on Win XP.

BUG=

TBR=tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/43019004

Cr-Commit-Position: refs/heads/master@{#8912}

webrtc/system_wrappers/source/event_timer_posix.h

@@ -1,60 +0,0 @@
-/*
- *  Copyright (c) 2011 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 WEBRTC_SYSTEM_WRAPPERS_SOURCE_EVENT_POSIX_H_
-#define WEBRTC_SYSTEM_WRAPPERS_SOURCE_EVENT_POSIX_H_
-
-#include "webrtc/system_wrappers/interface/event_wrapper.h"
-
-#include <pthread.h>
-#include <time.h>
-
-#include "webrtc/system_wrappers/interface/thread_wrapper.h"
-
-namespace webrtc {
-
-enum State {
-  kUp = 1,
-  kDown = 2
-};
-
-class EventTimerPosix : public EventTimerWrapper {
- public:
-  EventTimerPosix();
-  ~EventTimerPosix() override;
-
-  EventTypeWrapper Wait(unsigned long max_time) override;
-  bool Set() override;
-
-  bool StartTimer(bool periodic, unsigned long time) override;
-  bool StopTimer() override;
-
- private:
-  static bool Run(void* obj);
-  bool Process();
-  EventTypeWrapper Wait(timespec* end_at);
-
- private:
-  pthread_cond_t  cond_;
-  pthread_mutex_t mutex_;
-  bool event_set_;
-
-  rtc::scoped_ptr<ThreadWrapper> timer_thread_;
-  rtc::scoped_ptr<EventTimerPosix> timer_event_;
-  timespec       created_at_;
-
-  bool          periodic_;
-  unsigned long time_;  // In ms
-  unsigned long count_;
-};
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_SYSTEM_WRAPPERS_SOURCE_EVENT_POSIX_H_