Add support for refreshing contents of providers which don't support watchers.

chrome/test/data/extensions/api_test/file_system_provider/mount/test.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 'use strict';
 
 /**
  * Runs all of the test cases, one by one.
  */
 chrome.test.runTests([
@@ skipping 136 matching lines @@
 
     chrome.fileSystemProvider.onMountRequested.addListener(
         onMountRequested);
     chrome.fileManagerPrivate.getProvidingExtensions(
         chrome.test.callbackPass(function(extensions) {
           chrome.test.assertEq(extensions.length, 1);
           chrome.test.assertEq(chrome.runtime.id, extensions[0].extensionId);
           chrome.test.assertEq(
               chrome.runtime.getManifest().name, extensions[0].name);
           chrome.test.assertFalse(extensions[0].configurable);
-          chrome.test.assertTrue(extensions[0].multipleMounts);
+          chrome.test.assertFalse(extensions[0].watchable);
+          chrome.test.assertFalse(extensions[0].multipleMounts);
           chrome.test.assertEq('network', extensions[0].source);
         }));
 
     chrome.fileManagerPrivate.addProvidedFileSystem(
         chrome.runtime.id,
         chrome.test.callbackPass(function() {}));
   }
 ]);