(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/pc/ice_server_parsing.h b/pc/ice_server_parsing.h
index f1c26c1..c73d803 100644
--- a/pc/ice_server_parsing.h
+++ b/pc/ice_server_parsing.h
@@ -8,15 +8,15 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef PC_ICESERVERPARSING_H_
-#define PC_ICESERVERPARSING_H_
+#ifndef PC_ICE_SERVER_PARSING_H_
+#define PC_ICE_SERVER_PARSING_H_
 
 #include <vector>
 
-#include "api/peerconnectioninterface.h"
-#include "api/rtcerror.h"
+#include "api/peer_connection_interface.h"
+#include "api/rtc_error.h"
 #include "p2p/base/port.h"
-#include "p2p/base/portallocator.h"
+#include "p2p/base/port_allocator.h"
 
 namespace webrtc {
 
@@ -33,4 +33,4 @@
 
 }  // namespace webrtc
 
-#endif  // PC_ICESERVERPARSING_H_
+#endif  // PC_ICE_SERVER_PARSING_H_