Reflect scanning status in command UI. Only allow import once scanning is complete.

ui/file_manager/file_manager/background/js/mock_volume_manager.js

Index: ui/file_manager/file_manager/background/js/mock_volume_manager.js
diff --git a/ui/file_manager/file_manager/background/js/mock_volume_manager.js b/ui/file_manager/file_manager/background/js/mock_volume_manager.js
index eeac5566cca8c7ddb5210707e36262e5e3cde8fc..aa1003916a19fee66c391763c0b9f2022ebb12e6 100644
--- a/ui/file_manager/file_manager/background/js/mock_volume_manager.js
+++ b/ui/file_manager/file_manager/background/js/mock_volume_manager.js
@@ -9,12 +9,14 @@
 function MockVolumeManager() {
   this.volumeInfoList = new cr.ui.ArrayDataModel([]);
 
-  this.volumeInfoList.push(MockVolumeManager.createMockVolumeInfo(
-      VolumeManagerCommon.VolumeType.DRIVE, 'drive',
-      str('DRIVE_DIRECTORY_LABEL')));
-  this.volumeInfoList.push(MockVolumeManager.createMockVolumeInfo(
-      VolumeManagerCommon.VolumeType.DOWNLOADS, 'downloads',
-      str('DOWNLOADS_DIRECTORY_LABEL')));
+  this.createVolumeInfo(
+      VolumeManagerCommon.VolumeType.DRIVE,
+      'drive',
+      str('DRIVE_DIRECTORY_LABEL'));
+  this.createVolumeInfo(
+      VolumeManagerCommon.VolumeType.DOWNLOADS,
+      'downloads',
+      str('DOWNLOADS_DIRECTORY_LABEL'));
 }
 
 /**
@@ -35,6 +37,23 @@ MockVolumeManager.installMockSingleton = function(opt_singleton) {
 };
 
 /**
+ * Creates, installs and returns a mock VolumeInfo instance.
+ *
+ * @param {!VolumeType} type
+ * @param {string} volumeId
+ * @param {string} label
+ *
+ * @return {!VolumeInfo}
+ */
+MockVolumeManager.prototype.createVolumeInfo =
+    function(type, volumeId, label) {
+  var volumeInfo =
+      MockVolumeManager.createMockVolumeInfo(type, volumeId, label);
+  this.volumeInfoList.push(volumeInfo);
+  return volumeInfo;
+};
+
+/**
  * Returns the corresponding VolumeInfo.
  *
  * @param {MockFileEntry} entry MockFileEntry pointing anywhere on a volume.