Use the touch highlight background for the emoji toggle

res/drawable/emoji_toggle_background.xml

@@ -1,13 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-
-    <item android:state_pressed="true"
-          android:drawable="@android:color/transparent" />
-
-    <item android:state_focused="true"
-          android:drawable="@android:color/transparent" />
-
-    <item android:drawable="@android:color/transparent" />
-
-</selector>

res/layout/conversation_activity.xml

@@ -82,7 +82,7 @@
                         android:layout_width="wrap_content"
                         android:layout_height="fill_parent"
                         android:layout_gravity="center_vertical"
-                        android:background="@drawable/emoji_toggle_background"
+                        android:background="@drawable/touch_highlight_background"
                         android:padding="10dp"/>
 
                 <EditText