Move Activity classes to own packages.

FilesActivity > manager/ManageActivity
DocumentsActivity > picker/PickActivity

Change-Id: If2efb07fbebbd6ef84aa744af17c8cbeac05d770
diff --git a/src/com/android/documentsui/NavigationViewManager.java b/src/com/android/documentsui/NavigationViewManager.java
index 8c0972b..1479ed4 100644
--- a/src/com/android/documentsui/NavigationViewManager.java
+++ b/src/com/android/documentsui/NavigationViewManager.java
@@ -81,7 +81,7 @@
         }
     }
 
-    void update() {
+    public void update() {
 
         // TODO: Looks to me like this block is never getting hit.
         if (mEnv.isSearchExpanded()) {