Inherit the navigation initiator when navigating instead of the parent/opener

Spec PR: https://github.com/w3c/webappsec-csp/pull/358

Bug: 905301, 894228, 836148
Change-Id: I43ada2266d42d1cd56dbe3c6dd89d115e878a83a
Reviewed-on: https://chromium-review.googlesource.com/c/1314633
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610850}
void ContentSecurityPolicy::ReportMixedContent(
    const KURL& mixed_url,
    RedirectStatus redirect_status) const {
  for (const auto& policy : policies_)
    policy->ReportMixedContent(mixed_url, redirect_status);
}

void ContentSecurityPolicy::ReportMixedContent(
    const KURL& mixed_url,
    RedirectStatus redirect_status) const {
  for (const auto& policy : policies_)
    policy->ReportMixedContent(mixed_url, redirect_status);
}
