Use DeviceDefault.Settings.Dark for systemui_theme

It was using DeviceDefault which is black in AOSP. It should be using
the blue grey primary color instead used by DeviceDefault.Settings.

Bug: 30748928
Change-Id: I7e7ed87f74f654f412c106a44906d7fba4e992dc
diff --git a/packages/SystemUI/res/values/styles.xml b/packages/SystemUI/res/values/styles.xml
index 1e3b841..c659acf 100644
--- a/packages/SystemUI/res/values/styles.xml
+++ b/packages/SystemUI/res/values/styles.xml
@@ -217,7 +217,7 @@
     <style name="Animation.StatusBar">
     </style>
 
-    <style name="systemui_theme" parent="@android:style/Theme.DeviceDefault" />
+    <style name="systemui_theme" parent="@*android:style/Theme.DeviceDefault.Settings.Dark" />
 
     <style name="systemui_theme_remote_input" parent="@android:style/Theme.DeviceDefault.Light">
         <item name="android:colorAccent">@color/remote_input_accent</item>