Handle sorted event.

BUG=438050
TEST=out/Release/browser_tests --gtest_filter=FileManagerJsTest.ListThumbnailLoader

Review URL: https://codereview.chromium.org/886503006

Cr-Commit-Position: refs/heads/master@{#314990}

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

@@ -10,16 +10,6 @@
  * is responsible to return dataUrls of valid thumbnails and fetch them with
  * proper priority.
  *
- * TODOs
- * The following list is a todo list for this class. This list will be deleted
- * after all of them are implemented.
- * * Done: Fetch thumbnails with range based priority control.
- * * Done: Implement cache size limitation.
- * * Done: Modest queueing for low priority thumbnail fetches.
- * * Handle other event types of FileListModel, e.g. sort.
- * * Done: Change ThumbnailLoader to directly return dataUrl.
- * * Handle file types for which generic images are used.
- *
  * @param {!FileListModel} dataModel A file list model.
  * @param {!MetadataCache} metadataCache Metadata cache.
  * @param {!Document} document Document.
@@ -89,8 +79,10 @@ function ListThumbnailLoader(
    */
   this.cursor_ = 0;
 
-  // TODO(yawano): Handle other event types of FileListModel, e.g. sort.
+  // TODO(yawano): Change FileListModel to dispatch change event for file
+  // change, and change this class to handle it.
   this.dataModel_.addEventListener('splice', this.onSplice_.bind(this));
+  this.dataModel_.addEventListener('sorted', this.onSorted_.bind(this));
 }
 
 ListThumbnailLoader.prototype.__proto__ = cr.EventTarget.prototype;
@@ -125,6 +117,17 @@ ListThumbnailLoader.prototype.onSplice_ = function(event) {
   this.continue_();
 }
 
+/**
+ * An event handler for sorted event of data model. When list is sorted, start
+ * to rescan items.
+ *
+ * @param {!Event} event Event
+ */
+ListThumbnailLoader.prototype.onSorted_ = function(event) {
+  this.cursor_ = this.beginIndex_;
+  this.continue_();
+}
+
 /**
  * Sets high priority range in the list.
  *

ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.html

@@ -10,6 +10,7 @@
 <script src="../../../../webui/resources/js/cr/ui.js"></script>
 <script src="../../../../webui/resources/js/cr/ui/array_data_model.js"></script>
 <script src="../../common/js/lru_cache.js"></script>
+<script src="../../common/js/util.js"></script>
 <script src="../../common/js/mock_entry.js"></script>
 <script src="../../common/js/unittest_util.js"></script>
 <script src="directory_contents.js"></script>

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

@@ -242,3 +242,30 @@ function testErrorHandling(callback) {
     return !!getOneCallbacks[entry3.toURL()];
   }), callback);
 }
+
+/**
+ * Test case for handling sorted event in data model.
+ */
+function testSortedEvent(callback) {
+  listThumbnailLoader.setHighPriorityRange(0, 2);
+  fileListModel.push(directory1, entry1, entry2, entry3, entry4, entry5);
+
+  resolveGetOneCallback(entry1.toURL());
+  resolveGetOneCallback(entry2.toURL());
+  assertEquals(0, Object.keys(getOneCallbacks).length);
+
+  // In order to assert that following task enqueues are fired by sorted event,
+  // wait until all thumbnail loads are completed.
+  reportPromise(waitUntil(function() {
+    return thumbnailLoadedEvents.length === 2;
+  }).then(function() {
+    // After the sort, list should be
+    // directory1, entry5, entry4, entry3, entry2, entry1.
+    fileListModel.sort('name', 'desc');
+
+    return waitUntil(function() {
+      return !!getOneCallbacks[entry5.toURL()] &&
+          !!getOneCallbacks[entry4.toURL()]
+    });
+  }), callback);
+}