[page_load_metrics] Add a NavigationThrottle for richer abort metrics

chrome/browser/page_load_metrics/observers/from_gws_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/from_gws_page_load_metrics_observer.h"
 
 #include "base/macros.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"
@@ skipping 425 matching lines @@
         internal::kHistogramFromGWSFirstTextPaint, 1);
     histogram_tester().ExpectBucketCount(
         internal::kHistogramFromGWSFirstTextPaint,
         timing.first_text_paint.value().InMilliseconds(), 1);
   } else {
     histogram_tester().ExpectTotalCount(
         internal::kHistogramFromGWSFirstTextPaint, 0);
   }
 }
 
-TEST_F(FromGWSPageLoadMetricsObserverTest, UnknownNavigationBeforeCommit) {
+TEST_F(FromGWSPageLoadMetricsObserverTest, NewNavigationBeforeCommit) {
   NavigateAndCommit(GURL(kGoogleSearchResultsUrl));
   StartNavigation(GURL("http://example.test"));
 
   // Simulate the user performing another navigation before commit.
-  StartNavigation(GURL("https://www.example.com"));
+  NavigateAndCommit(GURL("https://www.example.com"));
   histogram_tester().ExpectTotalCount(
-      internal::kHistogramFromGWSAbortUnknownNavigationBeforeCommit, 1);
+      internal::kHistogramFromGWSAbortNewNavigationBeforeCommit, 1);
 }
 
 TEST_F(FromGWSPageLoadMetricsObserverTest, NewNavigationBeforePaint) {
   NavigateAndCommit(GURL(kGoogleSearchResultsUrl));
   NavigateAndCommit(GURL("http://example.test"));
   SimulateTimingWithoutPaint();
   // Simulate the user performing another navigation before paint.
   NavigateAndCommit(GURL("https://www.example.com"));
   histogram_tester().ExpectTotalCount(
       internal::kHistogramFromGWSAbortNewNavigationBeforePaint, 1);
@@ skipping 448 matching lines @@
       logger.ShouldLogPostCommitMetrics(GURL("https://www.google.com/about/")));
 }
 
 TEST_F(FromGWSPageLoadMetricsLoggerTest, NavigationFromSearchRedirector) {
   FromGWSPageLoadMetricsLogger logger;
   logger.SetPreviouslyCommittedUrl(
       GURL("https://www.google.com/url?source=web"));
   logger.set_navigation_initiated_via_link(true);
   ASSERT_TRUE(logger.ShouldLogPostCommitMetrics(GURL(kExampleUrl)));
 }