Server push cancellation: add PushPromiseHelper which reflects information on the push promise.

net/quic/core/quic_client_promised_info.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_client_promised_info.h"
 
 #include "base/logging.h"
 #include "net/quic/core/spdy_utils.h"
 
 using net::SpdyHeaderBlock;
@@ skipping 93 matching lines @@
 }
 
 QuicAsyncStatus QuicClientPromisedInfo::HandleClientRequest(
     const SpdyHeaderBlock& request_headers,
     QuicClientPushPromiseIndex::Delegate* delegate) {
   if (session_->IsClosedStream(id_)) {
     // There was a RST on the response stream.
     session_->DeletePromised(this);
     return QUIC_FAILURE;
   }
+
+  if (is_validating()) {
+    return QUIC_FAILURE;
+  }
+
   client_request_delegate_ = delegate;
   client_request_headers_.reset(new SpdyHeaderBlock(request_headers.Clone()));
   if (!response_headers_) {
     return QUIC_PENDING;
   }
   return FinalValidation();
 }
 
 void QuicClientPromisedInfo::Cancel() {
   // Don't fire OnRendezvousResult() for client initiated cancel.
   client_request_delegate_ = nullptr;
   Reset(QUIC_STREAM_CANCELLED);
 }
 
 }  // namespace net