Fix fallback in Metadata Cache.

ui/file_manager/file_manager/foreground/js/metadata/metadata_cache.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * MetadataCache is a map from Entry to an object containing properties.
  * Properties are divided by types, and all properties of one type are accessed
  * at once.
  * Some of the properties:
  * {
@@ skipping 340 matching lines @@
 
     fetchedCallbacks.push(onFetched);
 
     // Querying now.
     if (fetchedCallbacks.length === 1)
       currentProvider.fetch(entry, type, onProviderProperties);
   };
 
   var tryNextProvider = function() {
     if (providers.length === 0) {
+      // If not found, then mark the property as unavailable, so it's not
+      // retrieved again.
+      if (!(type in item.properties))
+        item.properties[type] = null;
+
       self.endBatchUpdates();
-      setTimeout(callback.bind(null, item.properties[type] || null), 0);
+      setTimeout(callback.bind(null, item.properties[type]), 0);
       return;
     }
 
     currentProvider = providers.shift();
     if (currentProvider.supportsEntry(entry) &&
         currentProvider.providesType(type)) {
       queryProvider();
     } else {
       tryNextProvider();
     }
@@ skipping 512 matching lines @@
     sharedWithMe: data.sharedWithMe,
     shared: data.shared,
     thumbnailUrl: data.thumbnailUrl  // Thumbnail passed from external server.
   };
 
   result.filesystem = {
     size: (entry.isFile ? (data.fileSize || 0) : -1),
     modificationTime: new Date(data.lastModifiedTime)
   };
 
-  if (data.isPresent) {
-    // If the file is present, don't fill the thumbnail here and allow to
-    // generate it by next providers.
-    result.thumbnail = null;
-  } else if ('thumbnailUrl' in data) {
-    result.thumbnail = {
-      url: data.thumbnailUrl,
-      transform: null
-    };
-  } else {
-    // Not present in cache, so do not allow to generate it by next providers.
-    result.thumbnail = {url: '', transform: null};
+  // TODO(mtomasz): Remove all of the if logic in the new metadata cache.
+  // If the file is not present, then use the thumbnail url instead of
+  // extracting the thumbnail from contents.
+  if (data.isPresent === false) {
+    if ('thumbnailUrl' in data) {
+      result.thumbnail = {
+        url: data.thumbnailUrl,
+        transform: null
+      };
+    } else {
+      // Not present in cache, so do not allow to generate it by next providers.
+      result.thumbnail = {url: '', transform: null};
+    }
   }
 
-  // If present in cache, then allow to fetch media by next providers.
-  result.media = data.isPresent ? null : {};
+  // If not present in cache, then do not allow to fetch media by next
+  // providers.
+  if (data.isPresent === false)
+    result.media = {};
 
   return result;
 };
 
 
 /**
  * Provider of content metadata.
  * This provider returns the following objects:
  * thumbnail: { url, transform }
  * media: { artist, album, title, width, height, imageTransform, etc. }
@@ skipping 179 matching lines @@
 
 /**
  * Handles the 'log' message from the worker.
  * @param {Array.<*>} arglist Log arguments.
  * @private
  */
 ContentProvider.prototype.onLog_ = function(arglist) {
   if (MetadataCache.log)  // Avoid log spam by default.
     console.log.apply(console, ['metadata:'].concat(arglist));
 };