Remove use of SEE_MASK_FLAG_NO_UI from Chrome Windows installer.

This flag was originally added to ui::base::win to suppress a specific
error message when attempting to open a file via the shell using the
"open" verb. The flag has additional side-effects and shouldn't be used
when invoking ShellExecute().

R=grt@chromium.org

Bug: 819809
Change-Id: I7db2344982dd206c85a73928e906c21e06a47a9e
Reviewed-on: https://chromium-review.googlesource.com/966964
Commit-Queue: Greg Thompson <grt@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544012}