Add icon for user switching

Only in the case of changing users, add a horizontal switch icon to
the top of the dialog.

Bug: 219075728
Test: manual (switch users and observe new icon)
Change-Id: I24d328a80c19339e1eef946d9fed69cb68615afb

core/res/res/drawable/ic_swap_horiz.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+ * Copyright 2022, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+-->
+<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="@android:color/white"
+      android:pathData="M17,14L15.6,12.575L18.175,10H11V8H18.175L15.6,5.425L17,4L22,9ZM7,20L2,15L7,10L8.4,11.425L5.825,14H13V16H5.825L8.4,18.575Z" />
+</vector>

core/res/res/layout/user_switching_dialog.xml

@@ -18,10 +18,13 @@
 <TextView xmlns:android="http://schemas.android.com/apk/res/android"
         android:id="@+id/message"
         style="?attr/textAppearanceListItem"
-        android:layout_width="match_parent"
+        android:background="?attr/colorSurface"
+        android:layout_width="wrap_content"
         android:layout_height="match_parent"
         android:gravity="center"
+        android:drawablePadding="12dp"
+        android:drawableTint="?attr/textColorPrimary"
         android:paddingStart="?attr/dialogPreferredPadding"
         android:paddingEnd="?attr/dialogPreferredPadding"
         android:paddingTop="24dp"
-        android:paddingBottom="24dp" />
+        android:paddingBottom="24dp" />

core/res/res/values/symbols.xml

@@ -4762,4 +4762,6 @@
   <java-symbol type="bool" name="config_bg_prompt_fgs_with_noti_to_bg_restricted" />
   <java-symbol type="integer" name="config_bg_current_drain_exempted_types" />
   <java-symbol type="bool" name="config_bg_current_drain_high_threshold_by_bg_location" />
+  <java-symbol type="drawable" name="ic_swap_horiz" />
+
 </resources>

services/core/java/com/android/server/am/UserSwitchingDialog.java

@@ -91,8 +91,8 @@ class UserSwitchingDialog extends AlertDialog
         setCancelable(false);
         Resources res = getContext().getResources();
         // Custom view due to alignment and font size requirements
-        View view = LayoutInflater.from(getContext()).inflate(R.layout.user_switching_dialog,
-            null);
+        TextView view = (TextView) LayoutInflater.from(getContext()).inflate(
+                R.layout.user_switching_dialog, null);
 
         String viewMessage = null;
         if (UserManager.isSplitSystemUser() && mNewUser.id == UserHandle.USER_SYSTEM) {
@@ -115,9 +115,12 @@ class UserSwitchingDialog extends AlertDialog
             if (viewMessage == null) {
                 viewMessage = res.getString(R.string.user_switching_message, mNewUser.name);
             }
+
+            view.setCompoundDrawablesWithIntrinsicBounds(null,
+                    getContext().getDrawable(R.drawable.ic_swap_horiz), null, null);
         }
         view.setAccessibilityPaneTitle(viewMessage);
-        ((TextView) view.findViewById(R.id.message)).setText(viewMessage);
+        view.setText(viewMessage);
         setView(view);
     }