Remove use of private APIs

Change-Id: I3e28763075f8e92391796dc009214c9fa8f50008
diff --git a/src/com/android/launcher2/FolderIcon.java b/src/com/android/launcher2/FolderIcon.java
index 2377f30..4a71329 100644
--- a/src/com/android/launcher2/FolderIcon.java
+++ b/src/com/android/launcher2/FolderIcon.java
@@ -601,7 +601,7 @@
 
     public void onTitleChanged(CharSequence title) {
         mFolderName.setText(title.toString());
-        setContentDescription(String.format(mContext.getString(R.string.folder_name_format),
+        setContentDescription(String.format(getContext().getString(R.string.folder_name_format),
                 title));
     }