Teach HistoryItem about a request's initiator.

third_party/WebKit/LayoutTests/http/tests/cookies/same-site/popup-cross-site.html

Index: third_party/WebKit/LayoutTests/http/tests/cookies/same-site/popup-cross-site.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/cookies/same-site/popup-cross-site.html b/third_party/WebKit/LayoutTests/http/tests/cookies/same-site/popup-cross-site.html
index 46f72465b4a79ae613282e6e494346326d518758..839aa5235ca4daa8f12477979a503190ea2a7a89 100644
--- a/third_party/WebKit/LayoutTests/http/tests/cookies/same-site/popup-cross-site.html
+++ b/third_party/WebKit/LayoutTests/http/tests/cookies/same-site/popup-cross-site.html
@@ -16,12 +16,20 @@ if (window.location.hostname == "127.0.0.1") {
 } else {
     async_test(t => {
         var i = window.open("http://" + ORIGINAL_HOST + ":8000/cookies/resources/post-cookies-to-opener.php");
-        window.addEventListener("message", t.step_func_done(e => {
+
+        var triggeredReload = false;
+        window.addEventListener("message", t.step_func(e => {
             assert_equals(e.data.http[STRICT_DOM], undefined, "strict");
             assert_equals(e.data.http[LAX_DOM], "1", "lax");
             assert_equals(e.data.http[NORMAL_DOM], "1", "normal");
             // TODO(mkwst): This should exclude the strict cookie.
             assert_equals(e.data.document, STRICT_DOM + "=1; " + LAX_DOM + "=1; " + NORMAL_DOM + "=1");
+            if (triggeredReload) {
+              t.done();
+            } else {
+              triggeredReload = true;
+              i.postMessage("reload", "*");
+            }
         }));
     }, "'" + ORIGINAL_HOST + "' is not same-site with '" + TEST_HOST + "', so strict samesite cookies are not sent.");
 }