Make extensions use a correct same-origin check.

GURL::GetOrigin does not do the right thing for all types of URLs.

BUG=573317

Review URL: https://codereview.chromium.org/1658913002

Cr-Commit-Position: refs/heads/master@{#373381}
ExtensionViewGuest::~ExtensionViewGuest() {
}

ExtensionViewGuest::~ExtensionViewGuest() {
}
