Switch private WebRTC desktop capture API to use IsOriginSecure() instead of SchemeIsSecure().

This mirrors the change in chrome/browser/extensions/api/desktop_capture/desktop_capture_api.cc in https://codereview.chromium.org/1131993005/

BUG=362214

Review URL: https://codereview.chromium.org/1138383007

Cr-Commit-Position: refs/heads/master@{#330057}
1 file changed