Gallery: Fix the slide show mode.

ui/file_manager/gallery/js/image_editor/image_view.js

Index: ui/file_manager/gallery/js/image_editor/image_view.js
diff --git a/ui/file_manager/gallery/js/image_editor/image_view.js b/ui/file_manager/gallery/js/image_editor/image_view.js
index 312fe726e42d58fd0e187dc959cdf7049855edcb..c85efad8588fdb56ae46a54f9edd5fa757b5bc00 100644
--- a/ui/file_manager/gallery/js/image_editor/image_view.js
+++ b/ui/file_manager/gallery/js/image_editor/image_view.js
@@ -129,10 +129,12 @@ ImageView.prototype.draw = function() {
  * change or offset change) with animation.
  */
 ImageView.prototype.applyViewportChange = function() {
-  this.setTransform(
-      this.screenImage_,
-      new ImageView.Effect.None(),
-      ImageView.Effect.DEFAULT_DURATION);
+  if (this.screenImage_) {
+    this.setTransform(
+        this.screenImage_,
+        new ImageView.Effect.None(),
+        ImageView.Effect.DEFAULT_DURATION);
+  }
 };
 
 /**