(4) Rename files to snake_case: update BUILD.gn, include paths, header guards, and DEPS entries

Mechanically generated by running this command:

tools_webrtc/do-renames.sh update all-renames.txt && git cl format

Then manually updating:

tools_webrtc/sanitizers/tsan_suppressions_webrtc.cc

Bug: webrtc:10159
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I54824cd91dada8fc3ee3d098f971bc319d477833
Reviewed-on: https://webrtc-review.googlesource.com/c/115653
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26226}
diff --git a/rtc_base/thread.h b/rtc_base/thread.h
index 039192c..e2d37a0 100644
--- a/rtc_base/thread.h
+++ b/rtc_base/thread.h
@@ -20,12 +20,12 @@
 #if defined(WEBRTC_POSIX)
 #include <pthread.h>
 #endif
-#include "rtc_base/constructormagic.h"
+#include "rtc_base/constructor_magic.h"
 #include "rtc_base/location.h"
-#include "rtc_base/messagehandler.h"
-#include "rtc_base/messagequeue.h"
+#include "rtc_base/message_handler.h"
+#include "rtc_base/message_queue.h"
 #include "rtc_base/platform_thread_types.h"
-#include "rtc_base/socketserver.h"
+#include "rtc_base/socket_server.h"
 #include "rtc_base/thread_annotations.h"
 
 #if defined(WEBRTC_WIN)