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}
diff --git a/test/testsupport/fileutils.h b/test/testsupport/fileutils.h
index 5ea7d31..f0560cf 100644
--- a/test/testsupport/fileutils.h
+++ b/test/testsupport/fileutils.h
@@ -10,13 +10,13 @@
 
 #include <stdio.h>
 
-#ifndef WEBRTC_TEST_TESTSUPPORT_FILEUTILS_H_
-#define WEBRTC_TEST_TESTSUPPORT_FILEUTILS_H_
+#ifndef TEST_TESTSUPPORT_FILEUTILS_H_
+#define TEST_TESTSUPPORT_FILEUTILS_H_
 
 #include <string>
 #include <vector>
 
-#include "webrtc/api/optional.h"
+#include "api/optional.h"
 
 namespace webrtc {
 namespace test {
@@ -107,4 +107,4 @@
 }  // namespace test
 }  // namespace webrtc
 
-#endif  // WEBRTC_TEST_TESTSUPPORT_FILEUTILS_H_
+#endif  // TEST_TESTSUPPORT_FILEUTILS_H_