When turning a download into a navigation, navigate the right frame

Code changes from Nate Chapin <japhet@chromium.org>

Bug: 926105
Change-Id: I098599394e6ebe7d2fce5af838014297a337d294
Reviewed-on: https://chromium-review.googlesource.com/c/1454962
Reviewed-by: Camille Lamy <clamy@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629547}
  scoped_refptr<FakeSafeBrowsingService> fake_safe_browsing_service() {
    return fake_safe_browsing_service_;
  }

  scoped_refptr<FakeSafeBrowsingService> fake_safe_browsing_service() {
    return fake_safe_browsing_service_;
  }
