Revert "Disable flaky MetricsWebContentsObserverBrowserTests"

chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc

 // Copyright (c) 2015 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/macros.h"
 #include "base/test/histogram_tester.h"
 #include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
@@ skipping 17 matching lines @@
 
 IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest, NoNavigation) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   histogram_tester_.ExpectTotalCount(internal::kHistogramCommit, 0);
   histogram_tester_.ExpectTotalCount(internal::kHistogramDomContentLoaded, 0);
   histogram_tester_.ExpectTotalCount(internal::kHistogramLoad, 0);
   histogram_tester_.ExpectTotalCount(internal::kHistogramFirstLayout, 0);
 }
 
-IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest,
-                       DISABLED_NewPage) {
+IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest, NewPage) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ui_test_utils::NavigateToURL(browser(),
                                embedded_test_server()->GetURL("/title1.html"));
   NavigateToUntrackedUrl();
 
   histogram_tester_.ExpectTotalCount(internal::kHistogramDomContentLoaded, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramLoad, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramFirstLayout, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramParseDuration, 1);
   histogram_tester_.ExpectTotalCount(
       internal::kHistogramParseBlockedOnScriptLoad, 1);
 }
 
 IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest,
-                       DISABLED_SamePageNavigation) {
+                       SamePageNavigation) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ui_test_utils::NavigateToURL(browser(),
                                embedded_test_server()->GetURL("/title1.html"));
   ui_test_utils::NavigateToURL(
       browser(), embedded_test_server()->GetURL("/title1.html#hash"));
   NavigateToUntrackedUrl();
 
   histogram_tester_.ExpectTotalCount(internal::kHistogramDomContentLoaded, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramLoad, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramFirstLayout, 1);
 }
 
 IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest,
-                       DISABLED_SameUrlNavigation) {
+                       SameUrlNavigation) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ui_test_utils::NavigateToURL(browser(),
                                embedded_test_server()->GetURL("/title1.html"));
   ui_test_utils::NavigateToURL(browser(),
                                embedded_test_server()->GetURL("/title1.html"));
   NavigateToUntrackedUrl();
 
   // We expect one histogram sample for each navigation to title1.html.
   histogram_tester_.ExpectTotalCount(internal::kHistogramCommit, 2);
@@ skipping 134 matching lines @@
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ui_test_utils::NavigateToURL(
       browser(), embedded_test_server()->GetURL(
                      "/page_load_metrics/document_write_no_script.html"));
   NavigateToUntrackedUrl();
 
   histogram_tester_.ExpectTotalCount(
       internal::kHistogramDocWriteBlockParseStartToFirstContentfulPaint, 0);
 }