Made toolbar title use the name of the current dir

It uses the name of the current directory, and if the directory is the
root directory, it uses the app name instead.

Change-Id: I1d8ac2545acb3e75be5b19fb5c208a8cb242de11
Reviewed-on: https://gerrit.libreoffice.org/35201Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Aleksandar Stefanović <theonewithideas@gmail.com>

android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java

@@ -103,6 +103,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
 
     private DrawerLayout drawerLayout;
     private NavigationView navigationDrawer;
+    private ActionBar actionBar;
     private ActionBarDrawerToggle drawerToggle;
     private RecyclerView fileRecyclerView;
     private RecyclerView recentRecyclerView;
@@ -136,7 +137,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
 
         Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
-        ActionBar actionBar = getSupportActionBar();
+        actionBar = getSupportActionBar();
 
         if (actionBar != null) {
             actionBar.setDisplayHomeAsUpEnabled(true);
@@ -373,11 +374,13 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
             recentRecyclerView.setVisibility(View.VISIBLE);
             findViewById(R.id.header_browser).setVisibility((View.VISIBLE));
             findViewById(R.id.header_recents).setVisibility((View.VISIBLE));
-
+            actionBar.setTitle(R.string.app_name);
         } else {
             recentRecyclerView.setVisibility(View.GONE);
             findViewById(R.id.header_browser).setVisibility((View.GONE));
             findViewById(R.id.header_recents).setVisibility((View.GONE));
+            actionBar.setTitle(dir.getName());
+
         }
 
         new AsyncTask<IFile, Void, Void>() {