Code: bool IsBlockedNavigation(net::Error error_code) {
  switch (error_code) {
    case net::ERR_BLOCKED_BY_CLIENT:
    case net::ERR_BLOCKED_BY_RESPONSE:
    case net::ERR_BLOCKED_BY_XSS_AUDITOR:
    case net::ERR_UNSAFE_REDIRECT:
      return true;
    default:
      return false;
  }
}

Vulnerability Type: 
CWE ID: CWE-20
Summary: Incorrect handling of back navigations in error pages in Navigation in Google Chrome prior to 63.0.3239.84 allowed a remote attacker to spoof the contents of the Omnibox (URL bar) via a crafted HTML page.
Commit Message: Do not use NavigationEntry to block history navigations.

This is no longer necessary after r477371.

BUG=777419
TEST=See bug for repro steps.

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_site_isolation
Change-Id: I701e4d4853858281b43e3743b12274dbeadfbf18
Reviewed-on: https://chromium-review.googlesource.com/733959
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: Charlie Reis <creis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#511942}