Fix wallpaper picker page TB issue

 - Setup activity title to make TalkBack announce title and response the result after updatnge toolbar title
 video for b/156873798: https://drive.google.com/file/d/1adjMNCCKYTH4lsq_j49vD6coHFNcDMoL/view?usp=sharing
 video for b/157964599: https://drive.google.com/file/d/1CpA-G7CXLMwCOeiu_JP79JpIOjKzPYkX/view?usp=sharing

 Fixes: 156873798
 Fixes: 157964599
 Test: manually

Change-Id: I385197fbaac37578e177a1a65e57ac7a8bddc75d
diff --git a/src/com/android/wallpaper/picker/AppbarFragment.java b/src/com/android/wallpaper/picker/AppbarFragment.java
index 7be36ba..b4db49f 100644
--- a/src/com/android/wallpaper/picker/AppbarFragment.java
+++ b/src/com/android/wallpaper/picker/AppbarFragment.java
@@ -111,6 +111,11 @@
         } else {
             mToolbar.setTitle(title);
         }
+
+        // Set Activity title to make TalkBack announce title after updating toolbar title.
+        if (getActivity() != null) {
+            getActivity().setTitle(title);
+        }
     }
 
     @Override