Add a refresh button for providers which do not support watchers.

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 61adeaa1ad02725114dee285cd4984728a2be67c..bfb6c2ef712b7214ae47d2ae2d69dbb520e90769 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
@@ -1424,3 +1424,22 @@ CommandHandler.COMMANDS_['configure'] = (function() {
   return new ConfigureCommand();
 })();
 
+/**
+ * Refreshes the currently selected directory.
+ */
+CommandHandler.COMMANDS_['refresh'] = /** @type {Command} */ ({
+  /**
+   * @param {!Event} event Command event.
+   * @param {!FileManager} fileManager FileManager to use.
+   */
+  execute: function(event, fileManager) {
+    // TODO(mtomasz): Implement refreshing.
+  },
+  canExecute: function(event, fileManager) {
+    var currentDirEntry = fileManager.directoryModel.getCurrentDirEntry();
+    var volumeInfo = fileManager.volumeManager.getVolumeInfo(currentDirEntry);
+    event.canExecute = !volumeInfo.watchable;

[fukino, 2015/07/01 10:39:33]

Could you add null check as volumeInfo can be null?

[mtomasz, 2015/07/02 08:52:40]

Done.

+    event.command.setHidden(!event.canExecute ||
+        fileManager.directoryModel.getFileListSelection().getCheckSelectMode());
+  }
+});