(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/api/jsep_session_description.h b/api/jsep_session_description.h
index 49b80fa..75ae0cd 100644
--- a/api/jsep_session_description.h
+++ b/api/jsep_session_description.h
@@ -11,8 +11,8 @@
 // TODO(deadbeef): Move this out of api/; it's an implementation detail and
 // shouldn't be used externally.
 
-#ifndef API_JSEPSESSIONDESCRIPTION_H_
-#define API_JSEPSESSIONDESCRIPTION_H_
+#ifndef API_JSEP_SESSION_DESCRIPTION_H_
+#define API_JSEP_SESSION_DESCRIPTION_H_
 
 #include <memory>
 #include <string>
@@ -21,8 +21,8 @@
 #include "absl/strings/string_view.h"
 #include "api/candidate.h"
 #include "api/jsep.h"
-#include "api/jsepicecandidate.h"
-#include "rtc_base/constructormagic.h"
+#include "api/jsep_ice_candidate.h"
+#include "rtc_base/constructor_magic.h"
 
 namespace cricket {
 class SessionDescription;
@@ -88,4 +88,4 @@
 
 }  // namespace webrtc
 
-#endif  // API_JSEPSESSIONDESCRIPTION_H_
+#endif  // API_JSEP_SESSION_DESCRIPTION_H_