Files.app: Add 'link' to the allowed effects in dataTransfer objects.

ui/file_manager/file_manager/common/js/util.js

Index: ui/file_manager/file_manager/common/js/util.js
diff --git a/ui/file_manager/file_manager/common/js/util.js b/ui/file_manager/file_manager/common/js/util.js
index 144e89e2ec8372dfc1b2deb3391f2aeb74b716da..e85d258ad89ce62525d4455ade44f0222bd577e9 100644
--- a/ui/file_manager/file_manager/common/js/util.js
+++ b/ui/file_manager/file_manager/common/js/util.js
@@ -1370,3 +1370,16 @@ util.getEntryLabel = function(volumeManager, entry) {
 
   return entry.name;
 };
+
+/**
+ * Checks if the specified set of allowed effects contains the given effect.
+ * See: http://www.w3.org/TR/html5/editing.html#the-datatransfer-interface
+ *
+ * @param {string} effectAllowed The string denoting the set of allowed effects.
+ * @param {string} dropEffect The effect to be checked.
+ * @return {boolean} True if |dropEffect| is included in |effectAllowed|.
+ */
+util.isDropEffectAllowed = function(effectAllowed, dropEffect) {
+  return effectAllowed === 'all' ||
+      effectAllowed.toLowerCase().indexOf(dropEffect) !== -1;
+};