Change ListThumbnailLoader to use ThumbnailLoader.loadAsDataUrl.

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

Index: ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
diff --git a/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js b/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
index a95b17bb5f18680ae8a4c2f13482fc0e4e177811..8c917f221f44d23a6d4340cbcb9563763fbbc087 100644
--- a/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
+++ b/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
@@ -58,7 +58,10 @@ function setUp() {
   ListThumbnailLoader.NUM_OF_MAX_ACTIVE_TASKS = 2;
   ListThumbnailLoader.NUM_OF_PREFETCH = 1;
   ListThumbnailLoader.CACHE_SIZE = 5;
-  MockThumbnailLoader.setTestImageDataUrl(generateSampleImageDataUrl(document));
+  MockThumbnailLoader.errorUrls = [];
+  MockThumbnailLoader.testImageDataUrl = generateSampleImageDataUrl(document);
+  MockThumbnailLoader.testImageWidth = 160;
+  MockThumbnailLoader.testImageHeight = 160;
 
   getOneCallbacks = {};
   var metadataCache = {
@@ -221,3 +224,21 @@ function testCache(callback) {
     });
   }), callback);
 }
+
+/**
+ * Test case for thumbnail fetch error. In this test case, thumbnail fetch for
+ * entry 2 is failed.
+ */
+function testErrorHandling(callback) {
+  MockThumbnailLoader.errorUrls = [entry2.toURL()];
+
+  listThumbnailLoader.setHighPriorityRange(0, 2);
+  fileListModel.push(entry1, entry2, entry3, entry4);
+
+  resolveGetOneCallback(entry2.toURL());
+
+  // Assert that new task is enqueued for entry3.
+  reportPromise(waitUntil(function() {
+    return !!getOneCallbacks[entry3.toURL()];
+  }), callback);
+}