Unify the way in which streams are marked unblocked after being converted from the pending status.

This does not change anything for existing code, but it does switch the order between SetUnblocked() and erase() on pending streams map, which is needed for a later WebTransport CL.

PiperOrigin-RevId: 364835817
Change-Id: I88f1a80271527c886dfe632aeff6430221ee1a1f
diff --git a/quic/core/quic_stream.h b/quic/core/quic_stream.h
index 822ec18..6e6e623 100644
--- a/quic/core/quic_stream.h
+++ b/quic/core/quic_stream.h
@@ -379,6 +379,10 @@
   // True if buffered data in send buffer is below buffered_data_threshold_.
   bool CanWriteNewData() const;
 
+  // Called immediately after the stream is created from a pending stream,
+  // indicating it can start processing data.
+  void OnStreamCreatedFromPendingStream();
+
  protected:
   // Called when data of [offset, offset + data_length] is buffered in send
   // buffer.