Add Widget related layout types to LayoutType

Bug: 177223401
Test: Manual
Change-Id: I990c25fe267499c8119e751e4d00c467c7a7f5ef
diff --git a/searchuilib/src/com/android/app/search/LayoutType.java b/searchuilib/src/com/android/app/search/LayoutType.java
index 9741b72..7208449 100644
--- a/searchuilib/src/com/android/app/search/LayoutType.java
+++ b/searchuilib/src/com/android/app/search/LayoutType.java
@@ -55,5 +55,12 @@
     // TODO: add diagram
     public static final String TEXT_HEADER = "header";
 
+
+    // Widget bitmap preview
+    public static final String WIDGET_PREVIEW = "widget_preview";
+
+    // Live widget search result
+    public static final String WIDGET_LIVE = "widget_live";
+
     // TODO: replace the plugin item types with these string constants
 }