Use FormatUrlForSecurityDisplay in WebUSB notification

This patch switches from using GURL::GetContext() to
url_formatter::FormatUrlForSecurityDisplay(OMIT_CRYPTOGRAPHIC) when
formatting the landing page URL for display in the WebUSB notification.
This means the path will no longer be displayed. For the time being we
believe this will be less confusing for users.

Bug: 773161
Change-Id: Ic32f2483b7316af21d3ec2521dd2483d4b00fd11
Reviewed-on: https://chromium-review.googlesource.com/720248
Reviewed-by: Lucas Garron <lgarron@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509108}
2 files changed