Remove base::SupportsWeakPtr from {Audio,Video}Sender

media/cast/sender/video_sender.h

Index: media/cast/sender/video_sender.h
diff --git a/media/cast/sender/video_sender.h b/media/cast/sender/video_sender.h
index 778ba0320e4d4bbdd3438667fe3793ddc24806b7..e383faa2509a75da1af55a6df91eecaf171e15e3 100644
--- a/media/cast/sender/video_sender.h
+++ b/media/cast/sender/video_sender.h
@@ -38,9 +38,7 @@ typedef base::Callback<void(base::TimeDelta)> PlayoutDelayChangeCB;
 // RTCP packets.
 // Additionally it posts a bunch of delayed tasks to the main thread for various
 // timeouts.
-class VideoSender : public FrameSender,
-                    public base::NonThreadSafe,
-                    public base::SupportsWeakPtr<VideoSender> {
+class VideoSender : public FrameSender, public base::NonThreadSafe {
  public:
   VideoSender(scoped_refptr<CastEnvironment> cast_environment,
               const FrameSenderConfig& video_config,
@@ -63,6 +61,8 @@ class VideoSender : public FrameSender,
   // the encoder does not have any such capability, returns null.
   std::unique_ptr<VideoFrameFactory> CreateVideoFrameFactory();
 
+  base::WeakPtr<VideoSender> AsWeakPtr();
+
  protected:
   int GetNumberOfFramesInEncoder() const final;
   base::TimeDelta GetInFlightMediaDuration() const final;