When launched into empty recents, show drawer.

Pull out drawer to give users more context about meaningful places
to navigate to.  Also fix bug where restored roots weren't being
highlighted.

Bug: 10852518
Change-Id: Id294f6923477ca4dc505c4b0a21a5bdf8b722cf4
diff --git a/src/com/android/documentsui/DirectoryFragment.java b/src/com/android/documentsui/DirectoryFragment.java
index 59caad0..d34fb07 100644
--- a/src/com/android/documentsui/DirectoryFragment.java
+++ b/src/com/android/documentsui/DirectoryFragment.java
@@ -291,6 +291,11 @@
 
                 updateDisplayState();
 
+                // When launched into empty recents, show drawer
+                if (mType == TYPE_RECENT_OPEN && mAdapter.isEmpty() && !state.stackTouched) {
+                    ((DocumentsActivity) context).setRootsDrawerOpen(true);
+                }
+
                 // Restore any previous instance state
                 final SparseArray<Parcelable> container = state.dirState.remove(mStateKey);
                 if (container != null && !getArguments().getBoolean(EXTRA_IGNORE_STATE, false)) {