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

net/quic/core/quic_client_session_base.h

Index: net/quic/core/quic_client_session_base.h
diff --git a/net/quic/core/quic_client_session_base.h b/net/quic/core/quic_client_session_base.h
index f73081f72aa54fb644d26c6639343b6bda89bf47..cb35e6dd2fcb39d643a266b71a2d72a7c69ca7ae 100644
--- a/net/quic/core/quic_client_session_base.h
+++ b/net/quic/core/quic_client_session_base.h
@@ -76,8 +76,9 @@ class NET_EXPORT_PRIVATE QuicClientSessionBase
   // Called by |QuicSpdyClientStream| on receipt of PUSH_PROMISE, does
   // some session level validation and creates the
   // |QuicClientPromisedInfo| inserting into maps by (promised) id and
-  // url.
-  virtual void HandlePromised(QuicStreamId associated_id,
+  // url. Returns true if a new push promise is accepted. Reset the promised and
+  // returns false otherwiese.
+  virtual bool HandlePromised(QuicStreamId associated_id,
                               QuicStreamId promised_id,
                               const SpdyHeaderBlock& headers);