[fuchsia] Do not set |local_endpoint| in Cast Streaming

openscreen::cast::Environment now has a default value set to any IPv6
address for the |local_endpoint| argument in the constructor. This
cleans up the usage in Cast Streaming.

Bug: 1096723
Change-Id: Id5f36a87acfb171d2aaeab7188c0b61ae864fa82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2252851
Auto-Submit: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: David Dorwin <ddorwin@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780077}

fuchsia/cast_streaming/cast_streaming_session.cc

@@ -44,10 +44,7 @@ class CastStreamingSession::Internal
       fidl::InterfaceRequest<fuchsia::web::MessagePort> message_port_request,
       scoped_refptr<base::SequencedTaskRunner> task_runner)
       : task_runner_(task_runner),
-        environment_(&openscreen::Clock::now,
-                     &task_runner_,
-                     openscreen::IPEndpoint{
-                         openscreen::IPAddress(0, 0, 0, 0, 0, 0, 0, 0), 0}),
+        environment_(&openscreen::Clock::now, &task_runner_),
         cast_message_port_impl_(std::move(message_port_request)),
         // TODO(crbug.com/1087520): Add streaming session Constraints and
         // DisplayDescription.