internal/lsp: add tracing to the didOpen call

We only had the tracing on didChange before this

Change-Id: Iadec8a43d439931bf58925f149a1d32b3ae29c36
Reviewed-on: https://go-review.googlesource.com/c/tools/+/186199
Run-TryBot: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index fb7608d..6544010 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -31,6 +31,8 @@
 	view := s.session.ViewOf(uri)
 	go func() {
 		ctx := view.BackgroundContext()
+		ctx, done := trace.StartSpan(ctx, "lsp:background-worker")
+		defer done()
 		s.Diagnostics(ctx, view, uri)
 	}()
 	return nil
@@ -69,7 +71,6 @@
 	// Run diagnostics on the newly-changed file.
 	go func() {
 		ctx := view.BackgroundContext()
-		//TODO: connect the remote span?
 		ctx, done := trace.StartSpan(ctx, "lsp:background-worker")
 		defer done()
 		s.Diagnostics(ctx, view, uri)