Gets rid of flickering when executing tests.

Achieves it by setting Executor background to white.

Change-Id: Id07c743114c6cce9e9446439136a5efd72857dc4

tests/DumpRenderTree2/AndroidManifest.xml

@@ -40,6 +40,7 @@ limitations under the License.
         </activity>
 
         <activity android:name=".LayoutTestsExecutor"
+                  android:theme="@style/WhiteBackground"
                   android:label="Layout tests' executor"
                   android:process=":executor">
         </activity>

tests/DumpRenderTree2/res/values/style.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+Copyright (C) 2010 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>
+    <style name="WhiteBackground">
+        <item name="android:background">@android:color/white</item>
+    </style>
+</resources>