Replace deprecated base::NonThreadSafe in content/renderer/media/webrtc in favor of SequenceChecker.

content/renderer/media/webrtc/media_stream_track_metrics.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_MEDIA_WEBRTC_MEDIA_STREAM_TRACK_METRICS_H_
 #define CONTENT_RENDERER_MEDIA_WEBRTC_MEDIA_STREAM_TRACK_METRICS_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <vector>
 
-#include "base/threading/non_thread_safe.h"
+#include "base/sequence_checker.h"
 #include "content/common/content_export.h"
 #include "third_party/webrtc/api/peerconnectioninterface.h"
 
 namespace webrtc {
 class MediaStreamInterface;
 }
 
 namespace content {
 
 class MediaStreamTrackMetricsObserver;
 class RTCPeerConnectionHandler;
 
 // Responsible for observing the connected lifetimes of tracks going
 // over a PeerConnection, and sending messages to the browser process
 // about lifetime events.
 //
 // There should be exactly one of these objects owned by each
 // RTCPeerConnectionHandler, and its lifetime should match the
 // lifetime of its owner.
-class CONTENT_EXPORT MediaStreamTrackMetrics : public base::NonThreadSafe {
+class CONTENT_EXPORT MediaStreamTrackMetrics {
  public:
   explicit MediaStreamTrackMetrics();
   ~MediaStreamTrackMetrics();
 
   enum StreamType { SENT_STREAM, RECEIVED_STREAM };
 
   enum TrackType { AUDIO_TRACK, VIDEO_TRACK };
 
   enum LifetimeEvent { CONNECTED, DISCONNECTED };
 
@@ skipping 47 matching lines @@
   // Make a unique ID for the given track, that is valid while the
   // track object and the PeerConnection it is attached to both exist.
   uint64_t MakeUniqueId(const std::string& track, StreamType stream_type);
 
   typedef std::vector<std::unique_ptr<MediaStreamTrackMetricsObserver>>
       ObserverVector;
   ObserverVector observers_;
 
   webrtc::PeerConnectionInterface::IceConnectionState ice_state_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(MediaStreamTrackMetrics);
 };
 
 }  // namespace
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBRTC_MEDIA_STREAM_TRACK_METRICS_H_