Flip quic_is_write_blocked to true to fix crash on cronet.

Details in internal bug 78282910.

Change-Id: Ie6a26f0f1ecbc937b83644e12ae9c87b6ef66410

Bug: 835425
Change-Id: Ie6a26f0f1ecbc937b83644e12ae9c87b6ef66410
Reviewed-on: https://chromium-review.googlesource.com/1022253
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Reviewed-by: Misha Efimov <mef@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552471}

net/quic/core/quic_flags_list.h

@@ -243,7 +243,7 @@ QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_unified_iw_options, false)
 
 // If true, check again that the writer isn\'t blocked before calling
 // QuicConnection::OnCanWrite from WriteAndBundleAcksIfNotBlocked
-QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_is_write_blocked, false)
+QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_is_write_blocked, true)
 
 // If true, use the send alarm instead of the resume_writes alarm in
 // QuicConnection.