Add support for parsing IETF format of alt-svc header advertising QUIC

This CL lands internal change 166256846 by wangyix.

BUG=488484

Change-Id: Idb25c187d402edc5e6c180c529fc3eede2c416bf
Reviewed-on: https://chromium-review.googlesource.com/620201
Commit-Queue: Yixin Wang <[email protected]>
Reviewed-by: Ryan Hamilton <[email protected]>
Cr-Commit-Position: refs/heads/master@{#510184}
diff --git a/net/http/http_network_session.h b/net/http/http_network_session.h
index ebbf81a..75d66c33 100644
--- a/net/http/http_network_session.h
+++ b/net/http/http_network_session.h
@@ -144,6 +144,9 @@
     // Retry requests which fail with QUIC_PROTOCOL_ERROR, and mark QUIC
     // broken if the retry succeeds.
     bool retry_without_alt_svc_on_quic_errors;
+    // If true, alt-svc headers advertising QUIC in IETF format will be
+    // supported.
+    bool support_ietf_format_quic_altsvc;
     // Specifies QUIC idle connection state lifetime.
     int quic_idle_connection_timeout_seconds;
     // Specifies the reduced ping timeout subsequent connections should use when