[Touchless] Remove bottom padding from list of options in touchless dialog.

This change removes whitespace between list items and bottom navbar.
Screenshot before (with old styling): http://screen/BMAx13oRGeP
Screenshot after: http://screen/4RB0K6kaYTX

BUG=959317
R=mdjones@chromium.org

Change-Id: I33927472dbb7c04639c80dd4314e388a92bd39a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1639352Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Pavel Yatsuk <pavely@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665679}

chrome/android/touchless/java/res/layout/touchless_dialog_view.xml

@@ -46,7 +46,8 @@
         android:id="@+id/touchless_dialog_option_list"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:padding="8dp"
+        android:paddingTop="8dp"
+        android:paddingHorizontal="8dp"
         android:divider="@android:color/transparent"
         android:dividerHeight="8dp"
         android:layout_gravity="center"