(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/peer_connection.cc b/pc/peer_connection.cc
index 2cf14a1..2d68c81 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -8,7 +8,7 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "pc/peerconnection.h"
+#include "pc/peer_connection.h"
 
 #include <algorithm>
 #include <limits>
@@ -19,37 +19,37 @@
 
 #include "absl/memory/memory.h"
 #include "absl/strings/match.h"
-#include "api/jsepicecandidate.h"
-#include "api/jsepsessiondescription.h"
-#include "api/mediastreamproxy.h"
-#include "api/mediastreamtrackproxy.h"
-#include "api/umametrics.h"
+#include "api/jsep_ice_candidate.h"
+#include "api/jsep_session_description.h"
+#include "api/media_stream_proxy.h"
+#include "api/media_stream_track_proxy.h"
+#include "api/uma_metrics.h"
 #include "call/call.h"
-#include "logging/rtc_event_log/icelogger.h"
+#include "logging/rtc_event_log/ice_logger.h"
 #include "logging/rtc_event_log/output/rtc_event_log_output_file.h"
 #include "logging/rtc_event_log/rtc_event_log.h"
-#include "media/sctp/sctptransport.h"
-#include "pc/audiotrack.h"
+#include "media/sctp/sctp_transport.h"
+#include "pc/audio_track.h"
 #include "pc/channel.h"
-#include "pc/channelmanager.h"
-#include "pc/dtmfsender.h"
-#include "pc/mediastream.h"
-#include "pc/mediastreamobserver.h"
-#include "pc/remoteaudiosource.h"
-#include "pc/rtpmediautils.h"
-#include "pc/rtpreceiver.h"
-#include "pc/rtpsender.h"
-#include "pc/sctputils.h"
-#include "pc/sdputils.h"
-#include "pc/streamcollection.h"
+#include "pc/channel_manager.h"
+#include "pc/dtmf_sender.h"
+#include "pc/media_stream.h"
+#include "pc/media_stream_observer.h"
+#include "pc/remote_audio_source.h"
+#include "pc/rtp_media_utils.h"
+#include "pc/rtp_receiver.h"
+#include "pc/rtp_sender.h"
+#include "pc/sctp_utils.h"
+#include "pc/sdp_utils.h"
+#include "pc/stream_collection.h"
 #include "pc/unique_id_generator.h"
-#include "pc/videocapturertracksource.h"
-#include "pc/videotrack.h"
+#include "pc/video_capturer_track_source.h"
+#include "pc/video_track.h"
 #include "rtc_base/bind.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/numerics/safe_conversions.h"
-#include "rtc_base/stringencode.h"
+#include "rtc_base/string_encode.h"
 #include "rtc_base/strings/string_builder.h"
 #include "rtc_base/trace_event.h"
 #include "system_wrappers/include/clock.h"