UI for AppRTC Android demo that doesn't require Design Support Library

webrtc/examples/androidapp/res/layout/activity_connect.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_margin="16dp"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical"
     android:weightSum="1"
     android:layout_centerHorizontal="true">
 
     <TextView
         android:id="@+id/room_edittext_description"
         android:layout_width="match_parent"
@@ skipping 15 matching lines @@
             android:singleLine="true"
             android:imeOptions="actionDone"
             android:inputType="text"/>
 
         <ImageButton
             android:id="@+id/connect_button"
             android:layout_width="48dp"
             android:layout_height="48dp"
             android:contentDescription="@string/connect_description"
             android:background="@android:drawable/sym_action_call" />
+
+        <ImageButton
+            android:id="@+id/add_favorite_button"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:contentDescription="@string/add_favorite_description"
+            android:background="@android:drawable/ic_input_add" />
     </LinearLayout>
 
     <TextView
         android:id="@+id/room_listview_description"
         android:layout_width="match_parent"
         android:layout_height="48dp"
         android:layout_marginTop="8dp"
         android:lines="1"
         android:maxLines="1"
         android:textAppearance="?android:attr/textAppearanceMedium"
@@ skipping 10 matching lines @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:drawSelectorOnTop="false" />
 
         <TextView
             android:id="@android:id/empty"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:gravity="center"
             android:text="@string/no_favorites" />
-
-        <android.support.design.widget.FloatingActionButton
-            android:id="@+id/add_favorite_button"
-            android:layout_width="56dp"
-            android:layout_height="56dp"
-            android:layout_margin="8dp"
-            android:layout_gravity="bottom|end"
-            android:src="@drawable/ic_add_white_24dp"
-            android:contentDescription="@string/add_favorite_description"
-            app:backgroundTint="@android:color/holo_green_dark"
-            app:elevation="8dp"/>
     </FrameLayout>
 </LinearLayout>