Only show Available Offline icon if file is fully downloaded

Bug: 1115025, 1128870
Change-Id: Ic3deb289f3730db92b717817f594cc7d9c969868
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419058Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Austin Tankiang <austinct@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809190}

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

@@ -3305,7 +3305,8 @@ body.files-ng #list-container li .detail-thumbnail {
   display: none;
 }
 
-body.files-ng #list-container li.pinned:not([renaming]) .detail-pinned {
+body.files-ng #list-container
+    li.pinned:not([renaming]):not(.dim-offline) .detail-pinned {
   -webkit-mask-image: url(../images/files/ui/offline.svg);
   -webkit-mask-position: center;
   -webkit-mask-repeat: no-repeat;