Make Talkback anounce which page is the icon being move on.

Adding a third argument for the talkback string.

Fix: 230593493
Test: Move an item using Talkback and it should mention the row,
column and page where you can drop the item.

Change-Id: Id3d4435e9ef3348278643e6e2a1cd1e8bf5157b7

src/com/android/launcher3/Workspace.java

@@ -3418,7 +3418,11 @@ public class Workspace<T extends View & PageIndicator> extends PagedView<T>
         return getPageDescription(page);
     }
 
-    private String getPageDescription(int page) {
+    /**
+     * @param page page index.
+     * @return Description of the page at the given page index.
+     */
+    public String getPageDescription(int page) {
         int nScreens = getChildCount();
         int extraScreenId = mScreenOrder.indexOf(EXTRA_EMPTY_SCREEN_ID);
         if (extraScreenId >= 0 && nScreens > 1) {