PDF: Remove comment about flaky test which has been fixed

chrome/browser/pdf/pdf_extension_test.cc

 // Copyright 2014 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.
 
 #include <vector>
 
 #include "base/base_paths.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/hash.h"
@@ skipping 524 matching lines @@
 IN_PROC_BROWSER_TEST_F(MaterialPDFExtensionTest, ZoomManager) {
   RunTestsInFile("zoom_manager_test.js", "test.pdf");
 }
 
 IN_PROC_BROWSER_TEST_F(MaterialPDFExtensionTest, Elements) {
   // Although this test file does not require a PDF to be loaded, loading the
   // elements without loading a PDF is difficult.
   RunTestsInFile("material_elements_test.js", "test.pdf");
 }
 
-// TODO(tsergeant): Verify that flake is fixed. http://crbug.com/550015
 IN_PROC_BROWSER_TEST_F(MaterialPDFExtensionTest, ToolbarManager) {
   RunTestsInFile("toolbar_manager_test.js", "test.pdf");
 }
 
 IN_PROC_BROWSER_TEST_F(MaterialPDFExtensionTest, Title) {
   RunTestsInFile("title_test.js", "test-title.pdf");
 }
 
 IN_PROC_BROWSER_TEST_F(MaterialPDFExtensionTest, WhitespaceTitle) {
   RunTestsInFile("whitespace_title_test.js", "test-whitespace-title.pdf");
 }
 
 IN_PROC_BROWSER_TEST_F(MaterialPDFExtensionTest, PageChange) {
   RunTestsInFile("page_change_test.js", "test-bookmarks.pdf");
 }