Added customizable default system theme.

Bug: 29266591
Change-Id: If0945abbda9e3560af5a6cdef394296b23c6de0c
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 107de8b..b21f5fb 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -181,7 +181,7 @@
      * visual content.
      */
     private static final int DEFAULT_SYSTEM_THEME =
-            com.android.internal.R.style.Theme_DeviceDefault_Light_DarkActionBar;
+            com.android.internal.R.style.Theme_DeviceDefault_System;
 
     private final int mFactoryTestMode;
     private Timer mProfilerSnapshotTimer;