Gallery: keep exif info if image is saved to a copy.

ui/file_manager/gallery/js/gallery_data_model_unittest.js

 // Copyright 2015 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.
 
 var model;
 var fileSystem;
 var item;
 
 /**
  * Mock thumbnail model.
  */
 function ThumbnailModel() {
 }
 
 ThumbnailModel.prototype.get = function(entries) {
   return Promise.resolve(entries.map(function() {
     return {};
   }));
 };
 
 function setUp() {
   model = new GalleryDataModel(
       /* Mock MetadataModel */{
         get: function() {
           return Promise.resolve([{}]);
         }
       },
       /* Mock EntryListWatcher */{});
   fileSystem = new MockFileSystem('volumeId');
+  model.fallbackSaveDirectory = fileSystem.root;
 }
 
 function testSaveItemOverwrite(callback) {
   var item = new Gallery.Item(
       new MockEntry(fileSystem, '/test.jpg'),
       null,
       /* metadataItem */ {},
       /* thumbnailMetadataItem */ {},
       /* original */ true);
 
@@ skipping 43 matching lines @@
           false /* not overwrite */).
           then(function() {
             assertEquals(2, model.length);
             assertEquals('test (1).png', model.item(0).getFileName());
             assertFalse(model.item(0).isOriginal());
             assertEquals('test.webp', model.item(1).getFileName());
             assertTrue(model.item(1).isOriginal());
           }),
       callback);
 }