Web Store will have an icon now!

Bug: 853349
Test: out/Default/ntp_render_browsertests
Change-Id: I46182b509b08d2772cb2a439f60f0a3313e5cb81
Reviewed-on: https://chromium-review.googlesource.com/1147105Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577578}