diff --git a/quic/core/quic_unacked_packet_map.cc b/quic/core/quic_unacked_packet_map.cc
index a18663f..e6328a7 100644
--- a/quic/core/quic_unacked_packet_map.cc
+++ b/quic/core/quic_unacked_packet_map.cc
@@ -529,4 +529,21 @@
   supports_multiple_packet_number_spaces_ = true;
 }
 
+uint32_t QuicUnackedPacketMap::GetLastPacketContent() const {
+  if (empty()) {
+    // Use max uint32_t to distinguish with packets with no retransmittable
+    // frames nor acks.
+    return std::numeric_limits<uint32_t>::max();
+  }
+  uint32_t content = 0;
+  const QuicTransmissionInfo& last_packet = unacked_packets_.back();
+  for (const auto& frame : last_packet.retransmittable_frames) {
+    content |= (1 << frame.type);
+  }
+  if (last_packet.largest_acked.IsInitialized()) {
+    content |= (1 << ACK_FRAME);
+  }
+  return content;
+}
+
 }  // namespace quic
diff --git a/quic/core/quic_unacked_packet_map.h b/quic/core/quic_unacked_packet_map.h
index 43e9008..61b2ea8 100644
--- a/quic/core/quic_unacked_packet_map.h
+++ b/quic/core/quic_unacked_packet_map.h
@@ -228,6 +228,12 @@
 
   void EnableMultiplePacketNumberSpacesSupport();
 
+  // Returns a bitfield of retransmittable frames of last packet in
+  // unacked_packets_. For example, if the packet contains STREAM_FRAME, content
+  // & (1 << STREAM_FRAME) would be set. Returns max uint32_t if
+  // unacked_packets_ is empty.
+  uint32_t GetLastPacketContent() const;
+
   Perspective perspective() const { return perspective_; }
 
   bool supports_multiple_packet_number_spaces() const {
diff --git a/quic/core/quic_unacked_packet_map_test.cc b/quic/core/quic_unacked_packet_map_test.cc
index 30482a3..330cc11 100644
--- a/quic/core/quic_unacked_packet_map_test.cc
+++ b/quic/core/quic_unacked_packet_map_test.cc
@@ -634,6 +634,8 @@
   EXPECT_EQ(QuicPacketNumber(4),
             unacked_packets_.GetLargestSentRetransmittableOfPacketNumberSpace(
                 APPLICATION_DATA));
+  EXPECT_TRUE(unacked_packets_.GetLastPacketContent() & (1 << STREAM_FRAME));
+  EXPECT_FALSE(unacked_packets_.GetLastPacketContent() & (1 << ACK_FRAME));
 }
 
 }  // namespace