Delete unused theme

PiperOrigin-RevId: 278638978

demos/surface/src/main/res/values/styles.xml

-<?xml version="1.0" encoding="utf-8"?>
-<!-- Copyright (C) 2019 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.
--->
-<resources xmlns:android="http://schemas.android.com/apk/res/android">
-
-  <style name="PlayerTheme" parent="android:Theme.Holo">
-    <item name="android:windowNoTitle">true</item>
-    <item name="android:windowBackground">@android:color/black</item>
-  </style>
-
-</resources>