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

ui/file_manager/gallery/js/gallery_data_model.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.
 
 /**
  * Data model for gallery.
  *
  * @param {!MetadataModel} metadataModel
  * @param {!EntryListWatcher=} opt_watcher Entry list watcher.
  * @constructor
@@ skipping 54 matching lines @@
  */
 GalleryDataModel.prototype.saveItem = function(
     volumeManager, item, canvas, overwrite) {
   var oldEntry = item.getEntry();
   var oldLocationInfo = item.getLocationInfo();
   var oldIsOriginal = item.isOriginal();
   return new Promise(function(fulfill, reject) {
     item.saveToFile(
         volumeManager,
         this.metadataModel_,
-        this.fallbackSaveDirectory,
+        assert(this.fallbackSaveDirectory),
         canvas,
         overwrite,
         function(success) {
           if (!success) {
             reject('Failed to save the image.');
             return;
           }
 
           // Current entry is updated.
           // Dispatch an event.
@@ skipping 76 matching lines @@
  * @private
  */
 GalleryDataModel.prototype.onSplice_ = function(event) {
   if (!event.removed || !event.removed.length)
     return;
   var removedURLs = event.removed.map(function(item) {
     return item.getEntry().toURL();
   });
   this.metadataModel_.notifyEntriesRemoved(removedURLs);
 };