Disable network diagnostics link in incognito and guest mode on Windows.

The link opens up the system diagnostics tool, if there is one. On
Windows, URLs the diagnostics tool is used on is logged to disk.

Bug: 929141
Change-Id: I4130279eec02e932cf846017bab2e8956d9b79f8
Reviewed-on: https://chromium-review.googlesource.com/c/1456685
Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Eric Roman <eroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629773}
5 files changed