(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/async_packet_socket.h b/rtc_base/async_packet_socket.h
index 0e31c2b..3afff3b 100644
--- a/rtc_base/async_packet_socket.h
+++ b/rtc_base/async_packet_socket.h
@@ -8,15 +8,15 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef RTC_BASE_ASYNCPACKETSOCKET_H_
-#define RTC_BASE_ASYNCPACKETSOCKET_H_
+#ifndef RTC_BASE_ASYNC_PACKET_SOCKET_H_
+#define RTC_BASE_ASYNC_PACKET_SOCKET_H_
 
-#include "rtc_base/constructormagic.h"
+#include "rtc_base/constructor_magic.h"
 #include "rtc_base/dscp.h"
 #include "rtc_base/network/sent_packet.h"
 #include "rtc_base/socket.h"
 #include "rtc_base/third_party/sigslot/sigslot.h"
-#include "rtc_base/timeutils.h"
+#include "rtc_base/time_utils.h"
 
 namespace rtc {
 
@@ -140,4 +140,4 @@
 
 }  // namespace rtc
 
-#endif  // RTC_BASE_ASYNCPACKETSOCKET_H_
+#endif  // RTC_BASE_ASYNC_PACKET_SOCKET_H_