[fuchsia] Remove outdated workaround

Bug: 768916, fuchsia:20638
Change-Id: Ibb6e1897661505c050c197cd30c853ba9bc115d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404622Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Tamir Duberstein <tamird@google.com>
Cr-Commit-Position: refs/heads/master@{#806102}

services/network/udp_socket_unittest.cc

@@ -689,12 +689,6 @@ TEST_F(UDPSocketTest, MAYBE_JoinMulticastGroup) {
   test::UDPSocketTestHelper helper(&socket_remote);
 
   mojom::UDPSocketOptionsPtr options = mojom::UDPSocketOptions::New();
-#if defined(OS_FUCHSIA)
-  // Fuchsia currently doesn't support automatic interface selection for
-  // multicast, so interface index needs to be set explicitly.
-  // See https://fuchsia.atlassian.net/browse/NET-195 .
-  options->multicast_interface = 1;
-#endif  // defined(OS_FUCHSIA)
   options->allow_address_sharing_for_multicast = true;
 
   net::IPAddress bind_ip_address;