Chrome Cleaner UI: Reporter no longer uses mojo.

The reporter will no longer use mojo to communicate with Chrome.
That will instead be the responsibility of the Chrome Cleaner process.

BUG=690020

Review-Url: https://codereview.chromium.org/2890023005
Cr-Original-Commit-Position: refs/heads/master@{#474778}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: bb6caf2e8acec41914ace77fdd974ca7a8b1c261