Revert of Disable flaky test

chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc

 // Copyright 2016 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 "base/command_line.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor_factory.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor_test_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 438 matching lines @@
       AddExternalResource(GetURL(kScriptDocumentWritePath),
                           content::RESOURCE_TYPE_SCRIPT, net::MEDIUM);
   externalScript->request.mime_type = kJavascriptMime;
   AddResource(GetURL(kImagePath), content::RESOURCE_TYPE_IMAGE, net::LOWEST);
   AddResource(GetURL(kStylePath), content::RESOURCE_TYPE_STYLESHEET,
               net::HIGHEST);
   AddResource(GetURL(kScriptPath), content::RESOURCE_TYPE_SCRIPT, net::MEDIUM);
   NavigateToURLAndCheckSubresources(GetURL(kHtmlDocumentWritePath));
 }
 
-// Disabled due to flakiness (crbug.com/673028).
 IN_PROC_BROWSER_TEST_F(ResourcePrefetchPredictorBrowserTest,
-                       DISABLED_LearningJavascriptAppendChild) {
+                       LearningJavascriptAppendChild) {
   auto externalScript =
       AddExternalResource(GetURL(kScriptAppendChildPath),
                           content::RESOURCE_TYPE_SCRIPT, net::MEDIUM);
   externalScript->request.mime_type = kJavascriptMime;
   AddResource(GetURL(kImagePath), content::RESOURCE_TYPE_IMAGE, net::LOWEST);
   AddResource(GetURL(kStylePath), content::RESOURCE_TYPE_STYLESHEET,
               net::HIGHEST);
   // This script has net::LOWEST priority because it's executed asynchronously.
   AddResource(GetURL(kScriptPath), content::RESOURCE_TYPE_SCRIPT, net::LOWEST);
   NavigateToURLAndCheckSubresources(GetURL(kHtmlAppendChildPath));
@@ skipping 40 matching lines @@
   AddResource(GetURL(kStylePath2), content::RESOURCE_TYPE_STYLESHEET,
               net::HIGHEST);
   AddResource(GetURL(kScriptPath2), content::RESOURCE_TYPE_SCRIPT, net::MEDIUM);
   // Included from <iframe src="html_subresources.html"> and not recored.
   AddUnrecordedResources({GetURL(kImagePath), GetURL(kStylePath),
                           GetURL(kScriptPath), GetURL(kFontPath)});
   NavigateToURLAndCheckSubresources(GetURL(kHtmlIframePath));
 }
 
 }  // namespace predictors