Show UI when a folder is empty.

ui/file_manager/file_manager/foreground/css/file_manager.css

Index: ui/file_manager/file_manager/foreground/css/file_manager.css
diff --git a/ui/file_manager/file_manager/foreground/css/file_manager.css b/ui/file_manager/file_manager/foreground/css/file_manager.css
index 7e940d8ea9f2d0e5e3d6378938be6f324bb0dae2..e50fc50104d8db15d8f6d58b7a046211af1ef2b9 100644
--- a/ui/file_manager/file_manager/foreground/css/file_manager.css
+++ b/ui/file_manager/file_manager/foreground/css/file_manager.css
@@ -1688,6 +1688,33 @@ body[drive='error'] #unmounted-panel > .error,
   display: block;
 }
 
+#empty-folder {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  justify-content: center;
+  left: 0;
+  position: absolute;
+  top: 0;
+  width: 100%;
+}
+
+#empty-folder > .image {
+  background-image: -webkit-image-set(
+      url(../images/files/ui/empty_folder.png) 1x,
+      url(../images/files/ui/2x/empty_folder.png) 2x);
+  height: 145px;
+  margin: 50px auto 32px auto;
+  width: 120px;
+}
+
+#empty-folder > .label {
+  color: rgb(180, 180, 180);
+  font-size: 16px;
+  font-weight: bold;
+  text-align: center;
+}
+
 #volume-space-info-contents {
   align-items: center;
   display: flex;