Remove use of gomobile now that Mojo uses Go v1.5.

Mojo just updated their Go compiler to v1.5, so the use of gomobile is
no longer necessary.

See https://codereview.chromium.org/1276653003

Change-Id: Idc7ef378e8c391f9ee497755a1207b6517f3664a
diff --git a/x/ref/services/syncbase/syncbased/mojo_main.go b/x/ref/services/syncbase/syncbased/mojo_main.go
index 2be9286..48272bb 100644
--- a/x/ref/services/syncbase/syncbased/mojo_main.go
+++ b/x/ref/services/syncbase/syncbased/mojo_main.go
@@ -10,15 +10,9 @@
 // cd $V23_ROOT/experimental/projects/ether
 // make gen/mojo/syncbased.mojo
 
-// TODO(sadovsky): Currently fails with error "flag provided but not defined:
-// -child-connection-id". Need to debug. Probably just need to peel off any Mojo
-// flags before having the Syncbase code do its flag parsing.
-
 import (
 	"log"
 
-	"golang.org/x/mobile/app"
-
 	"mojo/public/go/application"
 	"mojo/public/go/bindings"
 	"mojo/public/go/system"
@@ -74,6 +68,6 @@
 	return C.MOJO_RESULT_OK
 }
 
-func main() {
-	app.Run(app.Callbacks{})
-}
+// NOTE(nlacasse): Mojo runs Go code by calling MojoMain().  The main() method
+// below is still needed because the Go tool won't build without it.
+func main() {}