Move quic_flags.h from net/quic/core to net/quic/platform and split into api and impl.

net/quic/core/congestion_control/bbr_sender.cc

Index: net/quic/core/congestion_control/bbr_sender.cc
diff --git a/net/quic/core/congestion_control/bbr_sender.cc b/net/quic/core/congestion_control/bbr_sender.cc
index 6207a12f8e444fe7742d88b04ae3669f5fcc1bef..666a9d7f62997bfc452ec7bb7a972cf50139ed2d 100644
--- a/net/quic/core/congestion_control/bbr_sender.cc
+++ b/net/quic/core/congestion_control/bbr_sender.cc
@@ -10,9 +10,9 @@
 #include "net/quic/core/congestion_control/rtt_stats.h"
 #include "net/quic/core/crypto/crypto_protocol.h"
 #include "net/quic/core/proto/cached_network_parameters.pb.h"
-#include "net/quic/core/quic_flags.h"
 #include "net/quic/platform/api/quic_bug_tracker.h"
 #include "net/quic/platform/api/quic_flag_utils.h"
+#include "net/quic/platform/api/quic_flags.h"
 #include "net/quic/platform/api/quic_logging.h"
 
 namespace net {
@@ -93,9 +93,9 @@ BbrSender::BbrSender(const RttStats* rtt_stats,
       pacing_gain_(1),
       congestion_window_gain_(1),
       congestion_window_gain_constant_(
-          static_cast<float>(base::GetFlag(FLAGS_quic_bbr_cwnd_gain))),
-      rtt_variance_weight_(static_cast<float>(
-          base::GetFlag(FLAGS_quic_bbr_rtt_variation_weight))),
+          static_cast<float>(GetQuicFlag(FLAGS_quic_bbr_cwnd_gain))),
+      rtt_variance_weight_(
+          static_cast<float>(GetQuicFlag(FLAGS_quic_bbr_rtt_variation_weight))),
       num_startup_rtts_(kRoundTripsWithoutGrowthBeforeExitingStartup),
       cycle_current_offset_(0),
       last_cycle_start_(QuicTime::Zero()),