Remove an absl::WrapUnique usage without absl/memory/memory.h include

absl::WrapUnique requires memory.h include on C++17 mode compile.

Bug: chromium:752720
Change-Id: Iaa958652727c8927831d8eecd223678328c7b3bd
Reviewed-on: https://webrtc-review.googlesource.com/c/122440
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Peter Slatala <psla@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26701}

logging/rtc_event_log/events/rtc_event_generic_ack_received.cc

@@ -21,9 +21,9 @@ RtcEventGenericAckReceived::CreateLogs(
   std::vector<std::unique_ptr<RtcEventGenericAckReceived>> result;
   int64_t time_us = rtc::TimeMicros();
   for (const AckedPacket& packet : acked_packets) {
-    result.push_back(absl::WrapUnique(new RtcEventGenericAckReceived(
+    result.emplace_back(new RtcEventGenericAckReceived(
         time_us, packet_number, packet.packet_number,
-        packet.receive_acked_packet_time_ms)));
+        packet.receive_acked_packet_time_ms));
   }
   return result;
 }