Add a new SpdyStream::Delegate method to handle trailers

net/spdy/spdy_proxy_client_socket.cc

Index: net/spdy/spdy_proxy_client_socket.cc
diff --git a/net/spdy/spdy_proxy_client_socket.cc b/net/spdy/spdy_proxy_client_socket.cc
index 39fbd60cf33d0e7e0a77d7c7f1fc87508ec1d85e..e6d521e1356d7cca7fc58b01afddac3727b560b1 100644
--- a/net/spdy/spdy_proxy_client_socket.cc
+++ b/net/spdy/spdy_proxy_client_socket.cc
@@ -496,6 +496,12 @@ void SpdyProxyClientSocket::OnDataSent()  {
                             ResetAndReturn(&write_callback_), rv));
 }
 
+void SpdyProxyClientSocket::OnTrailers(const SpdyHeaderBlock& trailers) {
+  // |spdy_stream_| is of type SPDY_BIDIRECTIONAL_STREAM, so trailers are
+  // combined with response headers and this method will not be calld.
+  NOTREACHED();
+}
+
 void SpdyProxyClientSocket::OnClose(int status)  {
   was_ever_used_ = spdy_stream_->WasEverUsed();
   spdy_stream_.reset();