添加退出按钮

app/src/main/res/drawable/ic_expand_more.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M16.59,8.59L12,13.17 7.41,8.59 6,10l6,6 6,-6 -1.41,-1.41z" />
+</vector>