(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/remote_audio_source.h b/pc/remote_audio_source.h
index 4d87331..399e7e3 100644
--- a/pc/remote_audio_source.h
+++ b/pc/remote_audio_source.h
@@ -8,8 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef PC_REMOTEAUDIOSOURCE_H_
-#define PC_REMOTEAUDIOSOURCE_H_
+#ifndef PC_REMOTE_AUDIO_SOURCE_H_
+#define PC_REMOTE_AUDIO_SOURCE_H_
 
 #include <list>
 #include <string>
@@ -17,8 +17,8 @@
 #include "api/call/audio_sink.h"
 #include "api/notifier.h"
 #include "pc/channel.h"
-#include "rtc_base/criticalsection.h"
-#include "rtc_base/messagehandler.h"
+#include "rtc_base/critical_section.h"
+#include "rtc_base/message_handler.h"
 
 namespace rtc {
 struct Message;
@@ -73,4 +73,4 @@
 
 }  // namespace webrtc
 
-#endif  // PC_REMOTEAUDIOSOURCE_H_
+#endif  // PC_REMOTE_AUDIO_SOURCE_H_