Fix focus issues on RV.

Don't set focusable=false - that's the wrong thing to do, per Yigit.
For now, just temporarily make the RV unfocusable while performing the
focus search for kb navigation.

BUG=27221751

Change-Id: I37ed77eb2aecf522a85c8a7c181e89c0bf73765d

packages/DocumentsUI/src/com/android/documentsui/dirlist/DirectoryFragment.java

@@ -193,11 +193,6 @@ public class DirectoryFragment extends Fragment implements DocumentsAdapter.Envi
 
         mRecView.setItemAnimator(new DirectoryItemAnimator(getActivity()));
 
-        // Make the RecyclerView unfocusable. This is needed in order for the focus search code in
-        // FocusManager to work correctly. Setting android:focusable=false in the layout xml doesn't
-        // work, for some reason.
-        mRecView.setFocusable(false);
-
         // TODO: Add a divider between views (which might use RecyclerView.ItemDecoration).
         if (DEBUG_ENABLE_DND) {
             setupDragAndDropOnDirectoryView(mRecView);

packages/DocumentsUI/src/com/android/documentsui/dirlist/FocusManager.java

@@ -158,7 +158,14 @@ class FocusManager implements View.OnFocusChangeListener {
         }
 
         if (searchDir != -1) {
+            // Focus search behaves badly if the parent RecyclerView is focused. However, focusable
+            // shouldn't be unset on RecyclerView, otherwise focus isn't properly restored after
+            // events that cause a UI rebuild (like rotating the device). Compromise: turn focusable
+            // off while performing the focus search.
+            // TODO: Revisit this when RV focus issues are resolved.
+            mView.setFocusable(false);
             View targetView = view.focusSearch(searchDir);
+            mView.setFocusable(true);
             // TargetView can be null, for example, if the user pressed <down> at the bottom
             // of the list.
             if (targetView != null) {