Chrome Version: r480850
This happens only with PlzNavigate(--enable-browser-side-navigation)

A regression happens for the tests:
* fast/loader/main-document-url-for-non-http-loads.html
* http/tests/cache/iframe-304-crash.html
* http/tests/history/post-replace-state-reload.html
* http/tests/loading/307-after-303-after-post.html
* http/tests/loading/redirect-methods.html
* http/tests/misc/window-dot-stop.html
* http/tests/navigation/location-reload-after-post.php

It looks like the problem is that in:
```
WebFrameTestClient::WillSendRequest([...]) {
[...]
  if (test_runner()->shouldDumpResourceLoadCallbacks()) {
    delegate_->PrintMessage(DescriptionSuitableForTestResult(request_url));
    delegate_->PrintMessage(" - willSendRequest <NSURLRequest URL ");
    delegate_->PrintMessage(
        DescriptionSuitableForTestResult(request_url).c_str());
    delegate_->PrintMessage(", main document URL ");
    delegate_->PrintMessage(URLDescription(main_document_url).c_str());
    delegate_->PrintMessage(", http method ");
    delegate_->PrintMessage(request.HttpMethod().Utf8().data());
    delegate_->PrintMessage(">\n");
  }
[...]
}
```

|main_document_url| is empty.