Accessibility fixes

1) Use a different content description for temporary new page
2) Use different accessibility description for add widget toast
3) Announce when an item is deleted
4) Announce when hovering over a drop target
5) Announce state during drag-n-drop and widget resize (similar to seekbar)

Bug: 23573321, 24057944
Change-Id: Icabb317625e70c78e11c0b4f99b9339172d93594

src/com/android/launcher3/DropTarget.java

@@ -19,6 +19,8 @@ package com.android.launcher3;
 import android.graphics.PointF;
 import android.graphics.Rect;
 
+import com.android.launcher3.accessibility.DragViewStateAnnouncer;
+
 /**
  * Interface defining an object that can receive a drag.
  *
@@ -64,6 +66,8 @@ public interface DropTarget {
         /** Defers removing the DragView from the DragLayer until after the drop animation. */
         public boolean deferDragViewCleanupPostAnimation = true;
 
+        public DragViewStateAnnouncer stateAnnouncer;
+
         public DragObject() {
         }