Updater: Apply rounded edges to all AlertDialogs

Change-Id: I1b7c03b46b0812218b663d18bd1940e337a66d79

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

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     SPDX-FileCopyrightText: 2015 The Android Open Source Project
+     SPDX-License-Identifier: Apache-2.0
+-->
+<inset xmlns:android="http://schemas.android.com/apk/res/android"
+    android:inset="16dp">
+    <shape android:shape="rectangle">
+        <corners android:radius="16dp"/>
+        <solid android:color="?android:attr/colorBackgroundFloating"/>
+    </shape>
+</inset>

app/src/main/res/values/styles.xml

@@ -8,6 +8,7 @@
         <item name="android:windowLightStatusBar">@bool/theme_is_light</item>
         <item name="android:windowLightNavigationBar">@bool/theme_is_light</item>
         <item name="android:windowBackground">@color/background</item>
+        <item name="alertDialogTheme">@style/AppTheme.AlertDialogTheme</item>
     </style>
 
     <style name="AppTheme.NoActionBar">
@@ -32,4 +33,8 @@
         <item name="android:dropDownVerticalOffset">8dp</item>
         <item name="android:dropDownHorizontalOffset">-16dp</item>
     </style>
+
+    <style name="AppTheme.AlertDialogTheme" parent="Theme.AppCompat.DayNight.Dialog.Alert">
+        <item name="android:windowBackground">@drawable/dialog_background</item>
+    </style>
 </resources>