Instantiate PageLoadTrackers for prerenders

chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.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 "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 259 matching lines @@
   CheckNoErrorEvents();
 }
 
 TEST_F(MetricsWebContentsObserverTest, DontLogPrerender) {
   PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
 
   content::WebContentsTester* web_contents_tester =
       content::WebContentsTester::For(web_contents());
   embedder_interface_->set_is_prerendering(true);
+  observer_->WasHidden();

[Charlie Harrison, 2016/09/22 14:51:24]

Does removing this cause the test to fail?

[Bryan McQuade, 2016/09/22 15:14:37]

I added a DCHECK(!started_in_foreground_); for the prerender case, to make sure
that bit gets set sanely for prerenders. As a result, I had to change this as
well.

[Charlie Harrison, 2016/09/22 15:16:31]

Ahh, right! LGTM that's what I want.

 
   web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
   web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl2));
   ASSERT_EQ(0, CountUpdatedTimingReported());
   ASSERT_EQ(0, CountCompleteTimingReported());
-  CheckErrorEvent(ERR_IPC_WITH_NO_RELEVANT_LOAD, 1);
-  CheckTotalErrorEvents();
+  CheckNoErrorEvents();
 }
 
 TEST_F(MetricsWebContentsObserverTest, DontLogNewTabPage) {
   PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
 
   content::WebContentsTester* web_contents_tester =
       content::WebContentsTester::For(web_contents());
   embedder_interface_->set_is_ntp(true);
 
@@ skipping 204 matching lines @@
 
   histogram_tester_.ExpectTotalCount(
       internal::kPageLoadCompletedAfterAppBackground, 2);
   histogram_tester_.ExpectBucketCount(
       internal::kPageLoadCompletedAfterAppBackground, false, 1);
   histogram_tester_.ExpectBucketCount(
       internal::kPageLoadCompletedAfterAppBackground, true, 1);
 }
 
 }  // namespace page_load_metrics