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

net/quic/core/quic_sent_packet_manager_test.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_sent_packet_manager.h"
 
 #include <memory>
 
-#include "net/quic/core/quic_flags.h"
+#include "net/quic/core/quic_pending_retransmission.h"
+#include "net/quic/platform/api/quic_flags.h"
 #include "net/quic/platform/api/quic_ptr_util.h"
 #include "net/quic/platform/api/quic_string_piece.h"
 #include "net/quic/test_tools/quic_config_peer.h"
 #include "net/quic/test_tools/quic_sent_packet_manager_peer.h"
 #include "net/quic/test_tools/quic_test_utils.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::AnyNumber;
 using testing::ElementsAre;
@@ skipping 1710 matching lines @@
   ExpectAck(1);
   EXPECT_CALL(*network_change_visitor_,
               OnPathMtuIncreased(kDefaultLength + 100));
   QuicAckFrame ack_frame = InitAckFrame(1);
   manager_.OnIncomingAck(ack_frame, clock_.Now());
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net