Adding fling-to-delete.

- Also fixing issue where the drop target icon changes color slower than the text.

Change-Id: I0bfa59da5d202016342f1c3de419ebcafd81ff6f

src/com/android/launcher2/ButtonDropTarget.java

@@ -18,7 +18,7 @@ package com.android.launcher2;
 
 import android.content.Context;
 import android.content.res.Resources;
-import android.graphics.Paint;
+import android.graphics.PointF;
 import android.graphics.Rect;
 import android.util.AttributeSet;
 import android.widget.TextView;
@@ -71,6 +71,10 @@ public class ButtonDropTarget extends TextView implements DropTarget, DragContro
     public void onDrop(DragObject d) {
     }
 
+    public void onFlingToDelete(DragObject d, int x, int y, PointF vec) {
+        // Do nothing
+    }
+
     public void onDragEnter(DragObject d) {
         d.dragView.setColor(mHoverColor);
     }