In QUIC, use using for alias declaration.

This is the preferred way according to go/cstyle#Aliases

PiperOrigin-RevId: 341926282
Change-Id: Ib70cdb37fbdc985dec9e862c60aacbae54510281
diff --git a/quic/core/quic_stream_sequencer_buffer_test.cc b/quic/core/quic_stream_sequencer_buffer_test.cc
index e6a8914..0ad7244 100644
--- a/quic/core/quic_stream_sequencer_buffer_test.cc
+++ b/quic/core/quic_stream_sequencer_buffer_test.cc
@@ -52,7 +52,7 @@
 
 static const size_t kBlockSizeBytes =
     QuicStreamSequencerBuffer::kBlockSizeBytes;
-typedef QuicStreamSequencerBuffer::BufferBlock BufferBlock;
+using BufferBlock = QuicStreamSequencerBuffer::BufferBlock;
 
 namespace {
 
@@ -864,7 +864,7 @@
 class QuicStreamSequencerBufferRandomIOTest
     : public QuicStreamSequencerBufferTest {
  public:
-  typedef std::pair<QuicStreamOffset, size_t> OffsetSizePair;
+  using OffsetSizePair = std::pair<QuicStreamOffset, size_t>;
 
   void SetUp() override {
     // Test against a larger capacity then above tests. Also make sure the last