(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/media_stream_interface.cc

@@ -0,0 +1,35 @@
+/*
+ *  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.
+ */
+
+#include "api/mediastreaminterface.h"
+
+namespace webrtc {
+
+const char MediaStreamTrackInterface::kVideoKind[] = "video";
+const char MediaStreamTrackInterface::kAudioKind[] = "audio";
+
+VideoTrackInterface::ContentHint VideoTrackInterface::content_hint() const {
+  return ContentHint::kNone;
+}
+
+bool AudioTrackInterface::GetSignalLevel(int* level) {
+  return false;
+}
+
+rtc::scoped_refptr<AudioProcessorInterface>
+AudioTrackInterface::GetAudioProcessor() {
+  return nullptr;
+}
+
+const cricket::AudioOptions AudioSourceInterface::options() const {
+  return {};
+}
+
+}  // namespace webrtc