Turn on some quic flags to see whether they are related with cronet perf...

Turn on some quic flags to see whether they are related with cronet perf regression: FLAGS_quic_reloadable_flag_quic_simplify_pacing_sender, FLAGS_quic_reloadable_flag_quic_incremental_loss_detection, FLAGS_quic_reloadable_flag_quic_early_retransmit_detects_in_flight_packet_lost.

R=rch@chromium.org

Bug: 842677
Change-Id: Ib31af2a2da05400bddbe1f852f5ca967dcfad8bf
Reviewed-on: https://chromium-review.googlesource.com/1061595Reviewed-by: Helen Li <xunjieli@chromium.org>
Commit-Queue: Fan Yang <fayang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559109}

net/third_party/quic/core/quic_flags_list.h

@@ -179,7 +179,7 @@ QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_unified_send_alarm, true)
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_no_mspc, true)
 
 // If true, simplify pacing sender logic.
-QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_simplify_pacing_sender, false)
+QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_simplify_pacing_sender, true)
 
 // Number of packets that the pacing sender allows in bursts during pacing.
 QUIC_FLAG(int32_t, FLAGS_quic_lumpy_pacing_size, 1)
@@ -194,7 +194,7 @@ QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_respect_ietf_header, true)
 // If true, detect losses from last largest lost packet number.
 QUIC_FLAG(bool,
           FLAGS_quic_reloadable_flag_quic_incremental_loss_detection,
-          false)
+          true)
 
 // If true, enable fast path in QuicStreamSendBuffer::FreeMemSlices.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_fast_free_mem_slice, true)
@@ -208,7 +208,7 @@ QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_enable_ack_decimation, false)
 QUIC_FLAG(
     bool,
     FLAGS_quic_reloadable_flag_quic_early_retransmit_detects_in_flight_packet_lost,
-    false)
+    true)
 
 // Enables the 1RTO connection option which only sends one packet on QUIC
 // retransmission timeout, instead of 2.