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

chrome/test/data/extensions/api_test/file_browser/mount_test/test.js

 // Copyright (c) 2012 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.
 
 // These have to be sync'd with file_manager_private_apitest.cc
 var expectedVolume1 = {
   volumeId: 'removable:mount_path1',
   volumeLabel: 'mount_path1',
   sourcePath: 'device_path1',
   volumeType: 'removable',
   deviceType: 'usb',
   devicePath: 'system_path_prefix1',
   isParentDevice: false,
   isReadOnly: false,
   hasMedia: false,
   configurable: false,
+  watchable: true,
   source: 'device',
   profile: {profileId: '', displayName: '', isCurrentProfile: true},
 };
 
 var expectedVolume2 = {
   volumeId: 'removable:mount_path2',
   volumeLabel: 'mount_path2',
   sourcePath: 'device_path2',
   volumeType: 'removable',
   deviceType: 'mobile',
   devicePath: 'system_path_prefix2',
   isParentDevice: true,
   isReadOnly: true,
   hasMedia: true,
   configurable: false,
+  // This is not an MTP device, so it's watchable.
+  // TODO(mtomasz): Add a test for a real MTP device.
+  watchable: true,
   source: 'device',
   profile: {profileId: '', displayName: '', isCurrentProfile: true}
 };
 
 var expectedVolume3 = {
   volumeId: 'removable:mount_path3',
   volumeLabel: 'mount_path3',
   sourcePath: 'device_path3',
   volumeType: 'removable',
   deviceType: 'optical',
   devicePath: 'system_path_prefix3',
   isParentDevice: true,
   isReadOnly: false,
   hasMedia: false,
   configurable: false,
+  watchable: true,
   source: 'device',
   profile: {profileId: '', displayName: '', isCurrentProfile: true}
 };
 
 var expectedDownloadsVolume = {
   volumeId: /^downloads:Downloads[^\/]*$/,
   volumeLabel: '',
   volumeType: 'downloads',
   isReadOnly: false,
   hasMedia: false,
   configurable: false,
+  watchable: true,
   source: 'system',
   profile: {profileId: '', displayName: '', isCurrentProfile: true}
 };
 
 var expectedDriveVolume = {
   volumeId: /^drive:drive[^\/]*$/,
   volumeLabel: '',
   sourcePath: /^\/special\/drive[^\/]*$/,
   volumeType: 'drive',
   isReadOnly: false,
   hasMedia: false,
   configurable: false,
+  watchable: true,
   source: 'network',
   profile: {profileId: '', displayName: '', isCurrentProfile: true}
 };
 
 var expectedArchiveVolume = {
   volumeId: 'archive:archive_mount_path',
   volumeLabel: 'archive_mount_path',
   sourcePath: /removable\/mount_path3\/archive.zip$/,
   volumeType: 'archive',
   isReadOnly: true,
   hasMedia: false,
   configurable: false,
+  watchable: true,
   source: 'file',
   profile: {profileId: '', displayName: '', isCurrentProfile: true}
 };
 
 var expectedProvidedVolume = {
   volumeId: 'provided:',
   volumeLabel: '',
   volumeType: 'provided',
   isReadOnly: true,
   hasMedia: false,
   configurable: true,
+  watchable: false,
   extensionId: 'testing-extension-id',
   source: 'network',
   mountContext: 'auto',
   fileSystemId: '',
   profile: {profileId: '', displayName: '', isCurrentProfile: true}
 };
 
 // List of expected mount points.
 // NOTE: this has to be synced with values in file_manager_private_apitest.cc
 //       and values sorted by volumeId.
@@ skipping 57 matching lines @@
               'getMountPoints returned wrong number of mount points.');
           for (var i = 0; i < expectedVolumeList.length; i++) {
             chrome.test.assertTrue(
                 validateObject(
                     result[i], expectedVolumeList[i], 'volumeMetadata'),
                 'getMountPoints result[' + i + '] not as expected');
           }
     }));
   }
 ]);