Desktop NTP: Visual improvements for tiles

Individual changes:
- Use ellipsis instead of fade for long titles
- Removed tile border
- Added tile shadows
- Adjusted tile hover and focus states
- Increased thumbnail size to fill whole tile
- Made tile background color slightly lighter

Bug: 734038
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I5772fba00f5df9fd109b7006364b369e085b2a9e
Reviewed-on: https://chromium-review.googlesource.com/538635
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#480441}
2 files changed