Added getIconSize method to PreviewLayoutRule interface.

This will be used in new Folder animation.

Bug: 35064148
Change-Id: I5573336c0b8a9db8d1e600b1e16de07f48f35a21

src/com/android/launcher3/folder/ClippedFolderIconLayoutRule.java

@@ -120,6 +120,11 @@ public class ClippedFolderIconLayoutRule implements FolderIcon.PreviewLayoutRule
         return scale * mBaselineIconScale;
     }
 
+    @Override
+    public float getIconSize() {
+        return mIconSize;
+    }
+
     @Override
     public int maxNumItems() {
         return MAX_NUM_ITEMS_IN_PREVIEW;