Moving LauncherAccessibilityDelegate to Launcher to associate it with
activity lifecycle.

Change-Id: Ib815505677fa7ed74bdcfe7141b1d9bea5d7143a
diff --git a/src/com/android/launcher3/ButtonDropTarget.java b/src/com/android/launcher3/ButtonDropTarget.java
index 61ac713..5a4ed2f 100644
--- a/src/com/android/launcher3/ButtonDropTarget.java
+++ b/src/com/android/launcher3/ButtonDropTarget.java
@@ -312,8 +312,7 @@
 
     @Override
     public void onClick(View v) {
-        LauncherAppState.getInstance().getAccessibilityDelegate()
-            .handleAccessibleDrop(this, null, null);
+        mLauncher.getAccessibilityDelegate().handleAccessibleDrop(this, null, null);
     }
 
     public int getTextColor() {