Add capability to spring load a root or directory.

Bug: 28242270
Change-Id: I5cbdb7734af8d78015a82fd7b38b1266576c9914
(cherry picked from commit b5e2714d63dc5e74cef69f590b41a161eeca7b80)
diff --git a/packages/DocumentsUI/src/com/android/documentsui/FilesActivity.java b/packages/DocumentsUI/src/com/android/documentsui/FilesActivity.java
index f067d5f..60c37aa 100644
--- a/packages/DocumentsUI/src/com/android/documentsui/FilesActivity.java
+++ b/packages/DocumentsUI/src/com/android/documentsui/FilesActivity.java
@@ -312,6 +312,13 @@
         }
     }
 
+    @Override
+    public void springOpenDirectory(DocumentInfo doc) {
+        assert(doc.isContainer());
+        assert(!doc.isArchive());
+        openContainerDocument(doc);
+    }
+
     /**
      * Launches an intent to view the specified document.
      */