[File Manager] Properly enable/disable Copy and Open for GData files in the offline mode.

chrome/browser/resources/file_manager/js/file_type.js

Index: chrome/browser/resources/file_manager/js/file_type.js
diff --git a/chrome/browser/resources/file_manager/js/file_type.js b/chrome/browser/resources/file_manager/js/file_type.js
index ce859602c22639384164ee581c7861fc9b104be5..170349bca2263df76946e31ae9c4437fd5e1ecda 100644
--- a/chrome/browser/resources/file_manager/js/file_type.js
+++ b/chrome/browser/resources/file_manager/js/file_type.js
@@ -216,3 +216,33 @@ FileType.canUseImageUrlForPreview = function(metadata, opt_size) {
       (metadata.width && metadata.height &&
       (metadata.width * metadata.height <= FileType.MAX_PREVIEW_PIXEL_COUNT)));
 };
+
+/**
+ * @param {GDataFileProperties} gdata GData file properties.
+ * @return {boolean} True of the file is available in the offline mode.
+ */
+FileType.isAvaliableOffline_ = function(gdata) {
+  return gdata.isPresent && !gdata.isHosted;
+};
+
+/**
+ * Check if all the specified files are available in the offline mode.
+ *
+ * @param {Array.<Entry>?} entries File entries, ignore if null.
+ * @param {Array.<string>} urls File urls.
+ * @param {function(booolean)} callback Function accepting the result.
+ */
+FileType.checkOfflineAvailability = function(entries, urls, callback) {
+  chrome.fileBrowserPrivate.getGDataFileProperties(urls,
+    function(gdata) {
+      var result = true;
+      for (var i = 0; i != gdata.length; i++) {
+        if ((entries && entries[i].isDirectory) ||
+            !FileType.isAvaliableOffline_(gdata[i])) {
+          result = false;
+          break;
+        }
+      }
+      callback(result);
+    });
+};