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/examples/unityplugin/classreferenceholder.h b/examples/unityplugin/classreferenceholder.h
index 7d9a71b..31d6efc 100644
--- a/examples/unityplugin/classreferenceholder.h
+++ b/examples/unityplugin/classreferenceholder.h
@@ -13,8 +13,8 @@
 // specific java class into JNI c++ side, so that our c++ code can
 // call those java functions.
 
-#ifndef WEBRTC_EXAMPLES_UNITYPLUGIN_CLASSREFERENCEHOLDER_H_
-#define WEBRTC_EXAMPLES_UNITYPLUGIN_CLASSREFERENCEHOLDER_H_
+#ifndef EXAMPLES_UNITYPLUGIN_CLASSREFERENCEHOLDER_H_
+#define EXAMPLES_UNITYPLUGIN_CLASSREFERENCEHOLDER_H_
 
 #include <jni.h>
 #include <map>
@@ -34,4 +34,4 @@
 
 }  // namespace unity_plugin
 
-#endif  // WEBRTC_EXAMPLES_UNITYPLUGIN_CLASSREFERENCEHOLDER_H_
+#endif  // EXAMPLES_UNITYPLUGIN_CLASSREFERENCEHOLDER_H_