Replace QuicheStringPiece with absl::string_view

Tested:
    TAP --sample ran all affected tests and none failed
    http://test/OCL:335945932:BASE:335945937:1602110731512:c7c81ae9
PiperOrigin-RevId: 336088354
Change-Id: I6d9d2f77f21475068efc61d3b2c3434f752fb3b2
diff --git a/quic/masque/masque_encapsulated_epoll_client.cc b/quic/masque/masque_encapsulated_epoll_client.cc
index 1f39862..934a8e5 100644
--- a/quic/masque/masque_encapsulated_epoll_client.cc
+++ b/quic/masque/masque_encapsulated_epoll_client.cc
@@ -27,7 +27,7 @@
     DCHECK(peer_address.IsInitialized());
     QUIC_DVLOG(1) << "MasquePacketWriter trying to write " << buf_len
                   << " bytes to " << peer_address;
-    quiche::QuicheStringPiece packet(buffer, buf_len);
+    absl::string_view packet(buffer, buf_len);
     client_->masque_client()->masque_client_session()->SendPacket(
         client_->session()->connection()->client_connection_id(),
         client_->session()->connection()->connection_id(), packet,