Turn QuicWriteBlockedList into an abstract interface.

Also fix a typo in a method name.

PiperOrigin-RevId: 517946673
diff --git a/quiche/quic/core/quic_stream_test.cc b/quiche/quic/core/quic_stream_test.cc
index a0837be..7afbb19 100644
--- a/quiche/quic/core/quic_stream_test.cc
+++ b/quiche/quic/core/quic_stream_test.cc
@@ -160,7 +160,7 @@
   MockQuicConnection* connection_;
   std::unique_ptr<MockQuicSession> session_;
   StrictMock<TestStream>* stream_;
-  QuicWriteBlockedList* write_blocked_list_;
+  QuicWriteBlockedListInterface* write_blocked_list_;
   QuicTime::Delta zero_;
   ParsedQuicVersionVector supported_versions_;
   QuicStreamId kTestStreamId = GetNthClientInitiatedBidirectionalStreamId(