(3) Rename files to snake_case: move the files

Mechanically generated with this command:

tools_webrtc/do-rename.sh move all-renames.txt

Bug: webrtc:10159
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I8b05b6eab9b9d18b29c2199bbea239e9add1e690
Reviewed-on: https://webrtc-review.googlesource.com/c/115481
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26225}

api/rtp_transceiver_interface.cc

@@ -0,0 +1,33 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/rtptransceiverinterface.h"
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+RtpTransceiverInit::RtpTransceiverInit() = default;
+
+RtpTransceiverInit::RtpTransceiverInit(const RtpTransceiverInit& rhs) = default;
+
+RtpTransceiverInit::~RtpTransceiverInit() = default;
+
+absl::optional<RtpTransceiverDirection>
+RtpTransceiverInterface::fired_direction() const {
+  return absl::nullopt;
+}
+
+void RtpTransceiverInterface::SetCodecPreferences(
+    rtc::ArrayView<RtpCodecCapability>) {
+  RTC_NOTREACHED() << "Not implemented";
+}
+
+}  // namespace webrtc