cros: Remove elipses on "Set Wallpaper" string

Elipses have been removed from context menu strings per request from UX.

Bug: 832850
Change-Id: I7d54dd75ac4b44b8c4aaaaba9fff008af1e7972b
Reviewed-on: https://chromium-review.googlesource.com/1050373Reviewed-by: Yury Khmel <khmel@chromium.org>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556828}

ash/ash_strings.grd

@@ -750,7 +750,7 @@ This file contains the strings for ash.
       </message>
 
       <message name="IDS_AURA_SET_DESKTOP_WALLPAPER" desc="The label used for change wallpaper in context menu">
-        Set wallpaper...
+        Set wallpaper
       </message>
 
       <message name="IDS_ASH_STATUS_TRAY_TRACING" desc="The status tray item indicating that performance tracing is running.">