Move ThreadWrapper to ProcessThread in base.

webrtc/system_wrappers/source/event_timer_posix.h

Index: webrtc/system_wrappers/source/event_timer_posix.h
diff --git a/webrtc/system_wrappers/source/event_timer_posix.h b/webrtc/system_wrappers/source/event_timer_posix.h
index 21c4ac702e721ffb1e0c32405d8f8c5fa613a40a..6e45b387f9889500a3b1fe003d589f9aa729a6fe 100644
--- a/webrtc/system_wrappers/source/event_timer_posix.h
+++ b/webrtc/system_wrappers/source/event_timer_posix.h
@@ -16,7 +16,7 @@
 #include <pthread.h>
 #include <time.h>
 
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
+#include "webrtc/base/platform_thread.h"
 
 namespace webrtc {
 
@@ -46,7 +46,7 @@ class EventTimerPosix : public EventTimerWrapper {
   pthread_mutex_t mutex_;
   bool event_set_;
 
-  rtc::scoped_ptr<ThreadWrapper> timer_thread_;
+  rtc::scoped_ptr<PlatformThread> timer_thread_;
   rtc::scoped_ptr<EventTimerPosix> timer_event_;
   timespec       created_at_;