Removing some methods from the DragSource

This makes is easier to create new DragSource and sets up
proper default values in DragOptions

Change-Id: I6cb0b1df41b9730cf29f785fe85fe7f0b573ee3a
diff --git a/src/com/android/launcher3/ButtonDropTarget.java b/src/com/android/launcher3/ButtonDropTarget.java
index 632e490..3759300 100644
--- a/src/com/android/launcher3/ButtonDropTarget.java
+++ b/src/com/android/launcher3/ButtonDropTarget.java
@@ -178,7 +178,7 @@
 
     @Override
     public void onDragStart(DropTarget.DragObject dragObject, DragOptions options) {
-        mActive = supportsDrop(dragObject.dragSource, dragObject.dragInfo);
+        mActive = supportsDrop(dragObject.dragInfo);
         mDrawable.setColorFilter(null);
         if (mCurrentColorAnim != null) {
             mCurrentColorAnim.cancel();
@@ -194,10 +194,10 @@
 
     @Override
     public final boolean acceptDrop(DragObject dragObject) {
-        return supportsDrop(dragObject.dragSource, dragObject.dragInfo);
+        return supportsDrop(dragObject.dragInfo);
     }
 
-    protected abstract boolean supportsDrop(DragSource source, ItemInfo info);
+    protected abstract boolean supportsDrop(ItemInfo info);
 
     @Override
     public boolean isDropEnabled() {