Remove DownloadFeedbackDialogView

The opt-in on DownloadFeedbackDialogView is very low, so remove it. At
the same time, refactor logic for reporting. The safe browsing
preferences are now checked within the DownloadProtectionService.

Bug: 827567
Change-Id: I1bed2d912b53504246f21a803f0095cd15ead125
Reviewed-on: https://chromium-review.googlesource.com/1238563
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594039}
8 files changed