Add contentDescription to Emoji palette

This CL adds content descriptions of:
- Emoji Category icon/label.
- Delete key
- Space key

Bug: 11452158
Change-Id: Ic00592c560b6265c880cd25f2e18cfd349b4620b
diff --git a/java/res/layout/suggestion_divider.xml b/java/res/layout/suggestion_divider.xml
index a8b78c0..1490951 100644
--- a/java/res/layout/suggestion_divider.xml
+++ b/java/res/layout/suggestion_divider.xml
@@ -23,5 +23,6 @@
     android:layout_width="wrap_content"
     android:layout_height="match_parent"
     android:src="@drawable/suggestions_strip_divider"
+    android:contentDescription="@null"
     android:padding="0dp"
     android:gravity="center" />