Fixing WebRTC after moving from src/webrtc to src/

In https://webrtc-review.googlesource.com/c/src/+/1560 we moved WebRTC
from src/webrtc to src/ (in order to preserve an healthy git history).
This CL takes care of fixing header guards, #include paths, etc...

NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
TBR=tommi@webrtc.org


Bug: chromium:611808
Change-Id: Iea91618212bee0af16aa3f05071eab8f93706578
Reviewed-on: https://webrtc-review.googlesource.com/1561
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19846}

rtc_base/thread.h

diff --git a/rtc_base/thread.h b/rtc_base/thread.h
index d072fac..b4ce7d7 100644
--- a/rtc_base/thread.h
+++ b/rtc_base/thread.h
@@ -8,8 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef WEBRTC_RTC_BASE_THREAD_H_
-#define WEBRTC_RTC_BASE_THREAD_H_
+#ifndef RTC_BASE_THREAD_H_
+#define RTC_BASE_THREAD_H_
 
 #include <algorithm>
 #include <list>
@@ -20,13 +20,13 @@
 #if defined(WEBRTC_POSIX)
 #include <pthread.h>
 #endif
-#include "webrtc/rtc_base/constructormagic.h"
-#include "webrtc/rtc_base/event.h"
-#include "webrtc/rtc_base/messagequeue.h"
-#include "webrtc/rtc_base/platform_thread_types.h"
+#include "rtc_base/constructormagic.h"
+#include "rtc_base/event.h"
+#include "rtc_base/messagequeue.h"
+#include "rtc_base/platform_thread_types.h"
 
 #if defined(WEBRTC_WIN)
-#include "webrtc/rtc_base/win32.h"
+#include "rtc_base/win32.h"
 #endif
 
 namespace rtc {
@@ -334,4 +334,4 @@
 
 }  // namespace rtc
 
-#endif  // WEBRTC_RTC_BASE_THREAD_H_
+#endif  // RTC_BASE_THREAD_H_