Add thumbnailMetadataItem to GalleryItem.

ui/file_manager/gallery/js/gallery_data_model_unittest.js

Index: ui/file_manager/gallery/js/gallery_data_model_unittest.js
diff --git a/ui/file_manager/gallery/js/gallery_data_model_unittest.js b/ui/file_manager/gallery/js/gallery_data_model_unittest.js
index f2b7a3abae0c0845c0c9be9bc386cfe6a68ed293..c54ce2d0c9edd3d93a2b154ab8b8c8b9067e4864 100644
--- a/ui/file_manager/gallery/js/gallery_data_model_unittest.js
+++ b/ui/file_manager/gallery/js/gallery_data_model_unittest.js
@@ -8,17 +8,15 @@ var fileSystem;
 var item;
 
 function setUp() {
-  var metadataCache = new MockMetadataCache();
   model = new GalleryDataModel(
-      metadataCache,
       /* Mock MetadataModel */{},
       /* Mock EntryListWatcher */{});
   fileSystem = new MockFileSystem('volumeId');
   item = new Gallery.Item(
       new MockEntry(fileSystem, '/test.jpg'),
       null,
-      {media: {mimeType: 'image/jpeg'}},
-      metadataCache,
+      /* metadataItem */ {},
+      /* thumbnailMetadataItem */ {},
       /* original */ true);
 }
 
@@ -26,6 +24,7 @@ function testSaveItemOverwrite(callback) {
   // Mocking the saveToFile method.
   item.saveToFile = function(
       volumeManager,
+      metadataModel,
       fallbackDir,
       overwrite,
       canvas,
@@ -44,6 +43,7 @@ function testSaveItemNewFile(callback) {
   // Mocking the saveToFile method.
   item.saveToFile = function(
       volumeManager,
+      metadataModel,
       fallbackDir,
       overwrite,
       canvas,