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

ui/file_manager/file_manager/background/js/volume_manager_unittest.js

Index: ui/file_manager/file_manager/background/js/volume_manager_unittest.js
diff --git a/ui/file_manager/file_manager/background/js/volume_manager_unittest.js b/ui/file_manager/file_manager/background/js/volume_manager_unittest.js
index 30cb335aa626e954cd4dfe27ff3d6698b9404a70..da2ade5939de4974c1d83d140465006c550b326b 100644
--- a/ui/file_manager/file_manager/background/js/volume_manager_unittest.js
+++ b/ui/file_manager/file_manager/background/js/volume_manager_unittest.js
@@ -93,6 +93,7 @@ function setUp() {
       isReadOnly: false,
       profile: getMockProfile(),
       configurable: false,
+      watchable: true,
       source: VolumeManagerCommon.Source.SYSTEM
     },
     {
@@ -102,6 +103,7 @@ function setUp() {
       isReadOnly: false,
       profile: getMockProfile(),
       configurable: false,
+      watchable: true,
       source: VolumeManagerCommon.Source.NETWORK
     }
   ];
@@ -191,6 +193,7 @@ function testMountArchiveAndUnmount(callback) {
           sourcePath: mountSourcePath,
           profile: getMockProfile(),
           configurable: false,
+          watchable: true,
           source: VolumeManagerCommon.Source.FILE
         }
       });
@@ -262,6 +265,7 @@ function testVolumeInfoListWhenReady(callback) {
       /* extensionid */ null,
       /* hasMedia */ false,
       /* configurable */ false,
+      /* watchable */ true,
       /* source */ VolumeManagerCommon.Source.FILE);
   list.add(volumeInfo);
   var promiseAfterAdd = list.whenVolumeInfoReady('volumeId');