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

net/quic/core/quic_client_promised_info.h

 // 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.
 
 #ifndef NET_QUIC_QUIC_CLIENT_PROMISED_INFO_H_
 #define NET_QUIC_QUIC_CLIENT_PROMISED_INFO_H_
 
 #include <sys/types.h>
 #include <string>
 
@@ skipping 60 matching lines @@
   // field list), the promise headers (taking the role of the "cached"
   // request), and the client request headers.
   SpdyHeaderBlock* request_headers() { return request_headers_.get(); }
 
   SpdyHeaderBlock* response_headers() { return response_headers_.get(); }
 
   QuicStreamId id() const { return id_; }
 
   const std::string url() const { return url_; }
 
+  // Return true if there's a request pending matching this push promise.
+  bool is_validating() const { return client_request_delegate_ != nullptr; }
+
  private:
   friend class test::QuicClientPromisedInfoPeer;
 
   class CleanupAlarm : public QuicAlarm::Delegate {
    public:
     explicit CleanupAlarm(QuicClientPromisedInfo* promised)
         : promised_(promised) {}
 
     void OnAlarm() override;
 
@@ skipping 13 matching lines @@
   // The promise will commit suicide eventually if it is not claimed
   // by a GET first.
   std::unique_ptr<QuicAlarm> cleanup_alarm_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicClientPromisedInfo);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CLIENT_PROMISED_INFO_H_