Remove reference to system theme

This change also introduces
 * Background for space key preview
 * Tune stone theme

Change-Id: I84fca0baf2392582da870d2ff77b3e99c28faf7b
diff --git a/java/res/values/keyboard-icons-black.xml b/java/res/values/keyboard-icons-black.xml
index 89631bb..4144b64 100644
--- a/java/res/values/keyboard-icons-black.xml
+++ b/java/res/values/keyboard-icons-black.xml
@@ -15,7 +15,7 @@
 -->
 
 <resources>
-    <style name="KeyboardIcons.Black" parent="android:Theme.Light">
+    <style name="KeyboardIcons.Black">
         <!-- Keyboard icons -->
         <item name="iconShiftKey">@drawable/sym_bkeyboard_shift</item>
         <item name="iconToSymbolKeyWithShortcut">@drawable/sym_bkeyboard_123_mic</item>
@@ -34,8 +34,8 @@
         <!-- LatinKeyboard icons -->
         <item name="autoCorrectionSpacebarLedIcon">@drawable/sym_keyboard_space_led</item>
         <item name="disabledShortcutIcon">@drawable/sym_keyboard_voice_off_holo</item>
-        <item name="spacebarArrowLeftIcon">@drawable/sym_keyboard_language_arrows_left</item>
-        <item name="spacebarArrowRightIcon">@drawable/sym_keyboard_language_arrows_right</item>
+        <item name="spacebarArrowLeftIcon">@null</item>
+        <item name="spacebarArrowRightIcon">@null</item>
         <item name="spacebarArrowPreviewLeftIcon">@drawable/sym_keyboard_feedback_language_arrows_left</item>
         <item name="spacebarArrowPreviewRightIcon">@drawable/sym_keyboard_feedback_language_arrows_right</item>
     </style>