Add dialog_room.xml

app/src/main/res/layout/dialog_room.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_width="match_parent"
+    android:layout_height="match_parent"
+    android:minWidth="300dp"
+    android:orientation="vertical">
+
+    <ImageButton
+        android:id="@+id/button_close"
+        android:layout_width="32dp"
+        android:layout_height="32dp"
+        android:scaleType="fitXY"
+        android:layout_marginBottom="@dimen/margin_32"
+        android:layout_gravity="end"
+        app:srcCompat="@drawable/ic_close_circle_outline_black_24dp"
+        android:background="?attr/selectableItemBackgroundBorderless" />
+
+    <TextView
+        android:id="@+id/text_message"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginBottom="@dimen/margin_32"
+        android:layout_gravity="center"
+        android:gravity="center"
+        android:visibility="gone" />
+
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/recycler_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:scrollbars="vertical" />
+</LinearLayout>
\ No newline at end of file