Flip back recent quic flags to verify cronet perf regression.

Suspected flags are flipped back to see if the cronet perf regression is fixed:
FLAGS_quic_reloadable_flag_quic_simplify_pacing_sender,
FLAGS_quic_reloadable_flag_quic_incremental_loss_detection,
FLAGS_quic_reloadable_flag_quic_enable_ack_decimation,
FLAGS_quic_reloadable_flag_quic_early_retransmit_detects_in_flight_packet_lost.

Bug: 842677
Change-Id: I86bbd84988de2f2eb5933d58d9c43c7a12a88b02
Reviewed-on: https://chromium-review.googlesource.com/1060426Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558890}

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, true)
+QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_simplify_pacing_sender, false)
 
 // Number of packets that the pacing sender allows in bursts during pacing.
 QUIC_FLAG(int32_t, FLAGS_quic_lumpy_pacing_size, 1)
@@ -192,23 +192,23 @@ QUIC_FLAG(double, FLAGS_quic_lumpy_pacing_cwnd_fraction, 0.25f)
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_respect_ietf_header, true)
 
 // If true, detect losses from last largest lost packet number.
-
-// If true, enable fast path in QuicStreamSendBuffer::FreeMemSlices.
 QUIC_FLAG(bool,
           FLAGS_quic_reloadable_flag_quic_incremental_loss_detection,
-          true);
+          false)
+
+// If true, enable fast path in QuicStreamSendBuffer::FreeMemSlices.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_fast_free_mem_slice, true)
 
 // Default enables QUIC ack decimation and adds a connection option to disable
 // it.
-QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_enable_ack_decimation, true)
+QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_enable_ack_decimation, false)
 
 // If true, declare in flight packets lost via early retransmit, even though it
 // has no retransmittable frames.
 QUIC_FLAG(
     bool,
     FLAGS_quic_reloadable_flag_quic_early_retransmit_detects_in_flight_packet_lost,
-    true)
+    false)
 
 // Enables the 1RTO connection option which only sends one packet on QUIC
 // retransmission timeout, instead of 2.