Delete webrtc::PacketTime and backwards compatibility.

This is a followup to
https://webrtc-review.googlesource.com/c/src/+/91840, which needed
transitional methods while updating downstream code. This cl completes
the deletion, and can be landed after downstream code is updated.

Bug: webtrc:9584
Change-Id: I4d3654748973a4757a8d79bb93f524c630a0eca3
Reviewed-on: https://webrtc-review.googlesource.com/93285
Commit-Queue: Oleh Prypin <oprypin@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24329}
diff --git a/call/packet_receiver.h b/call/packet_receiver.h
index 2a0e3ef..f05e409 100644
--- a/call/packet_receiver.h
+++ b/call/packet_receiver.h
@@ -31,13 +31,7 @@
 
   virtual DeliveryStatus DeliverPacket(MediaType media_type,
                                        rtc::CopyOnWriteBuffer packet,
-                                       int64_t packet_time_us);
-
-  // TODO(bugs.webrtc.org/9584): Deprecated. Over the transition, default
-  // implementations are used, and subclasses must override one or the other.
-  virtual DeliveryStatus DeliverPacket(MediaType media_type,
-                                       rtc::CopyOnWriteBuffer packet,
-                                       const PacketTime& packet_time);
+                                       int64_t packet_time_us) = 0;
 
  protected:
   virtual ~PacketReceiver() {}