Create test for default grid

Fixes: 256044695
Test: DeviceDefaultGridTest
Change-Id: Ie0a4de12f777ad3d15020252b2f67b575cc0eca9
diff --git a/src/com/android/launcher3/Utilities.java b/src/com/android/launcher3/Utilities.java
index f70511a..a507532 100644
--- a/src/com/android/launcher3/Utilities.java
+++ b/src/com/android/launcher3/Utilities.java
@@ -521,6 +521,11 @@
         return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
     }
 
+    /** Converts a dp value to pixels for a certain density. */
+    public static int dpToPx(float dp, int densityDpi) {
+        float densityRatio = (float) densityDpi / DisplayMetrics.DENSITY_DEFAULT;
+        return (int) (dp * densityRatio);
+    }
 
     public static int pxFromSp(float size, DisplayMetrics metrics) {
         return pxFromSp(size, metrics, 1f);