Revert of Refoctoring FileSelection and FileSelectionHandler.

ui/file_manager/file_manager/foreground/js/file_manager_commands.js

Index: ui/file_manager/file_manager/foreground/js/file_manager_commands.js
diff --git a/ui/file_manager/file_manager/foreground/js/file_manager_commands.js b/ui/file_manager/file_manager/foreground/js/file_manager_commands.js
index 1d684d058b15f439d9aaa42e1c71604d8038d61a..3b1bf35ec005fdb4878c5f6583f9f1e2c3cd0d62 100644
--- a/ui/file_manager/file_manager/foreground/js/file_manager_commands.js
+++ b/ui/file_manager/file_manager/foreground/js/file_manager_commands.js
@@ -107,6 +107,23 @@
 };
 
 /**
+ * Returns a single selected/passed entry or null.
+ * @param {!Event} event Command event.
+ * @param {!FileManager} fileManager FileManager to use.
+ * @return {FileEntry} The entry or null.
+ */
+CommandUtil.getSingleEntry = function(event, fileManager) {
+  if (event.target.entry) {
+    return event.target.entry;
+  }
+  var selection = fileManager.getSelection();
+  if (selection.totalCount == 1) {
+    return selection.entries[0];
+  }
+  return null;
+};
+
+/**
  * Obtains target entries that can be pinned from the selection.
  * If directories are included in the selection, it just returns an empty
  * array to avoid confusing because pinning directory is not supported
@@ -219,7 +236,7 @@
     return null;
   if (!selection.entries[0].isDirectory)
     return null;
-  return /** @type {!DirectoryEntry} */(selection.entries[0]);
+  return selection.entries[0];
 };
 
 /**