Remove dependency on non-Blink variants from SecurityOrigin StructTraits

Bug: 891686
Change-Id: I5770942e18ee8a9221f322101bcc2793d74d3695
Reviewed-on: https://chromium-review.googlesource.com/c/1262617Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596844}

third_party/blink/renderer/platform/mojo/security_origin_struct_traits.h

@@ -8,7 +8,6 @@
 #include "third_party/blink/renderer/platform/weborigin/security_origin.h"
 #include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
 #include "url/mojom/origin.mojom-blink.h"
-#include "url/mojom/origin_mojom_traits.h"
 
 namespace mojo {