(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/setremotedescriptionobserverinterface.h

@@ -1,31 +0,0 @@
-/*
- *  Copyright 2017 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.
- */
-
-#ifndef API_SETREMOTEDESCRIPTIONOBSERVERINTERFACE_H_
-#define API_SETREMOTEDESCRIPTIONOBSERVERINTERFACE_H_
-
-#include "api/rtcerror.h"
-#include "rtc_base/refcount.h"
-
-namespace webrtc {
-
-// An observer for PeerConnectionInterface::SetRemoteDescription(). The
-// callback is invoked such that the state of the peer connection can be
-// examined to accurately reflect the effects of the SetRemoteDescription
-// operation.
-class SetRemoteDescriptionObserverInterface : public rtc::RefCountInterface {
- public:
-  // On success, |error.ok()| is true.
-  virtual void OnSetRemoteDescriptionComplete(RTCError error) = 0;
-};
-
-}  // namespace webrtc
-
-#endif  // API_SETREMOTEDESCRIPTIONOBSERVERINTERFACE_H_