Compiling file_manager, part 2: remove all warnings not caused by Object.freeze()-like enums

ui/file_manager/image_loader/image_loader_client.js

Index: ui/file_manager/image_loader/image_loader_client.js
diff --git a/ui/file_manager/image_loader/image_loader_client.js b/ui/file_manager/image_loader/image_loader_client.js
index 5876e20d375a14eb96fa0262f61f5bca38c9c516..6e2ba137249f39f6c90f88f49c9e06b2b88bb67b 100644
--- a/ui/file_manager/image_loader/image_loader_client.js
+++ b/ui/file_manager/image_loader/image_loader_client.js
@@ -123,7 +123,7 @@ ImageLoaderClient.prototype.handleMessage_ = function(message) {
  * @param {function} callback Callback used to return response.
  * @param {Object=} opt_options Loader options, such as: scale, maxHeight,
  *     width, height and/or cache.
- * @param {function=} opt_isValid Function returning false in case
+ * @param {function(): boolean=} opt_isValid Function returning false in case
  *     a request is not valid anymore, eg. parent node has been detached.
  * @return {?number} Remote task id or null if loaded from cache.
  */