[page_load_metrics] Add a NavigationThrottle for richer abort metrics

chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc

 // Copyright 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 "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
 
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h"
 #include "chrome/browser/page_load_metrics/page_load_metrics_util.h"
 #include "chrome/test/base/testing_browser_process.h"
@@ skipping 311 matching lines @@
 
   web_contents()->WasHidden();
 
   // Open in new tab
   StartNavigation(GURL(kDefaultTestUrl));
 
   // Switch to the tab
   web_contents()->WasShown();
 
   // Start another provisional load
-  StartNavigation(GURL(kDefaultTestUrl2));
-  content::RenderFrameHostTester* rfh_tester =
-      content::RenderFrameHostTester::For(main_rfh());
-  rfh_tester->SimulateNavigationCommit(GURL(kDefaultTestUrl2));
+  NavigateAndCommit(GURL(kDefaultTestUrl2));
   SimulateTimingUpdate(timing);
-  rfh_tester->SimulateNavigationStop();
 
   // Navigate again to see if the timing updated for the foregrounded load.
   NavigateAndCommit(GURL(kDefaultTestUrl));
 
   histogram_tester().ExpectTotalCount(internal::kHistogramCommit, 1);
   histogram_tester().ExpectTotalCount(internal::kHistogramDomContentLoaded, 0);
   histogram_tester().ExpectTotalCount(internal::kHistogramLoad, 0);
   histogram_tester().ExpectTotalCount(internal::kHistogramFirstLayout, 1);
   histogram_tester().ExpectBucketCount(internal::kHistogramFirstLayout,
                                        first_layout.InMilliseconds(), 1);
@@ skipping 197 matching lines @@
   histogram_tester().ExpectTotalCount(
       internal::kHistogramLoadTypeParseStartReload, 0);
   histogram_tester().ExpectTotalCount(
       internal::kHistogramLoadTypeParseStartForwardBack, 0);
   histogram_tester().ExpectTotalCount(
       internal::kHistogramLoadTypeParseStartNewNavigation, 1);
   histogram_tester().ExpectBucketCount(
       internal::kHistogramLoadTypeParseStartNewNavigation,
       timing.parse_start.value().InMilliseconds(), 1);
 }