Add PushResponse() in QuicSimpleServerStream.

net/tools/quic/quic_simple_server_stream.h

Index: net/tools/quic/quic_simple_server_stream.h
diff --git a/net/tools/quic/quic_simple_server_stream.h b/net/tools/quic/quic_simple_server_stream.h
index 8e6c94face96da358b91c46bd1524e13e469a8b7..aa31ef2057547ea6001424e8b4fa5e96b7d8b53b 100644
--- a/net/tools/quic/quic_simple_server_stream.h
+++ b/net/tools/quic/quic_simple_server_stream.h
@@ -37,6 +37,11 @@ class QuicSimpleServerStream : public QuicSpdyStream {
   // data (or a FIN) to be read.
   void OnDataAvailable() override;
 
+  // Make this stream start from as if it just finished parsing an incoming
+  // request whose headers are equivalent to |push_request_headers|.
+  // Doing so will trigger this toy stream to fetch response and send it back.
+  virtual void PushResponse(SpdyHeaderBlock push_request_headers);
+
   // The response body of error responses.
   static const char* const kErrorResponseBody;