Create a QuicChromiumClientStream::Handle class for allowing a stream

net/quic/chromium/quic_http_stream.h

Index: net/quic/chromium/quic_http_stream.h
diff --git a/net/quic/chromium/quic_http_stream.h b/net/quic/chromium/quic_http_stream.h
index fe240f84c98dc39f9de8d2f3b2a9000fcdd1570d..eb490005203285d520cc1f938137088d60ceb2f3 100644
--- a/net/quic/chromium/quic_http_stream.h
+++ b/net/quic/chromium/quic_http_stream.h
@@ -81,6 +81,9 @@ class NET_EXPORT_PRIVATE QuicHttpStream
   bool CheckVary(const SpdyHeaderBlock& client_request,
                  const SpdyHeaderBlock& promise_request,
                  const SpdyHeaderBlock& promise_response) override;
+  // TODO(rch): QuicClientPushPromiseIndex::Delegate is part of shared code.
+  // Figure out how to make the QuicHttpStream receive a Handle in this
+  // case instead of a QuicSpdyStream.
   void OnRendezvousResult(QuicSpdyStream* stream) override;
 
   static HttpResponseInfo::ConnectionInfo ConnectionInfoFromQuicVersion(
@@ -152,7 +155,7 @@ class NET_EXPORT_PRIVATE QuicHttpStream
 
   HttpServerProperties* http_server_properties_;  // Unowned.
 
-  QuicChromiumClientStream* stream_;  // Non-owning.
+  std::unique_ptr<QuicChromiumClientStream::Handle> stream_;
 
   // The following three fields are all owned by the caller and must
   // outlive this object, according to the HttpStream contract.