Show open task button only when applicable.

ui/file_manager/file_manager/foreground/js/file_manager.js

Index: ui/file_manager/file_manager/foreground/js/file_manager.js
diff --git a/ui/file_manager/file_manager/foreground/js/file_manager.js b/ui/file_manager/file_manager/foreground/js/file_manager.js
index 86a137637c36f19cc4dd85dd9f30e5a42233a8cc..667e70aa0a7de025659bc6bd6b8a88b01a982992 100644
--- a/ui/file_manager/file_manager/foreground/js/file_manager.js
+++ b/ui/file_manager/file_manager/foreground/js/file_manager.js
@@ -548,7 +548,7 @@ FileManager.prototype = /** @struct */ {
         assert(this.metadataModel_), assert(this.selectionHandler_),
         assert(this.ui_.listContainer), assert(this.quickViewModel_),
         assert(this.taskController_), fileListSelectionModel,
-        assert(this.quickViewUma_), metadataBoxController);
+        assert(this.quickViewUma_), metadataBoxController, this.dialogType);
 
     if (this.dialogType === DialogType.FULL_PAGE) {
       importer.importEnabled().then(