[Prerender] first contentful paint histograms.

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 91 matching lines @@
     completed_filtered_urls_->push_back(extra_info.committed_url);
   }
 
  private:
   std::vector<GURL>* const completed_filtered_urls_;
 };
 
 class TestPageLoadMetricsEmbedderInterface
     : public PageLoadMetricsEmbedderInterface {
  public:
-  TestPageLoadMetricsEmbedderInterface()
-      : is_prerendering_(false), is_ntp_(false) {}
+  TestPageLoadMetricsEmbedderInterface() : is_ntp_(false) {}
 
-  bool IsPrerendering(content::WebContents* web_contents) override {
-    return is_prerendering_;
-  }
   bool IsNewTabPageUrl(const GURL& url) override { return is_ntp_; }
-  void set_is_prerendering(bool is_prerendering) {
-    is_prerendering_ = is_prerendering;
-  }
   void set_is_ntp(bool is_ntp) { is_ntp_ = is_ntp; }
   void RegisterObservers(PageLoadTracker* tracker) override {
     tracker->AddObserver(base::MakeUnique<TestPageLoadMetricsObserver>(
         &updated_timings_, &complete_timings_, &observed_committed_urls_));
     tracker->AddObserver(base::MakeUnique<FilteringPageLoadMetricsObserver>(
         &completed_filtered_urls_));
   }
   const std::vector<PageLoadTiming>& updated_timings() const {
     return updated_timings_;
   }
   const std::vector<PageLoadTiming>& complete_timings() const {
     return complete_timings_;
   }
 
   // currently_committed_urls passed to OnStart().
   const std::vector<GURL>& observed_committed_urls_from_on_start() const {
     return observed_committed_urls_;
   }
 
   // committed URLs passed to FilteringPageLoadMetricsObserver::OnComplete().
   const std::vector<GURL>& completed_filtered_urls() const {
     return completed_filtered_urls_;
   }
 
  private:
   std::vector<PageLoadTiming> updated_timings_;
   std::vector<PageLoadTiming> complete_timings_;
   std::vector<GURL> observed_committed_urls_;
   std::vector<GURL> completed_filtered_urls_;
-  bool is_prerendering_;
   bool is_ntp_;
 };
 
 }  //  namespace
 
 class MetricsWebContentsObserverTest : public ChromeRenderViewHostTestHarness {
  public:
   MetricsWebContentsObserverTest() : num_errors_(0) {}
 
   void SetUp() override {
@@ skipping 153 matching lines @@
   // Navigate again to force histogram logging.
   web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl2));
 
   // A same page navigation shouldn't trigger logging UMA for the original.
   ASSERT_EQ(1, CountUpdatedTimingReported());
   ASSERT_EQ(1, CountCompleteTimingReported());
   ASSERT_EQ(0, CountEmptyCompleteTimingReported());
   CheckNoErrorEvents();
 }
 
-TEST_F(MetricsWebContentsObserverTest, DontLogPrerender) {

[Charlie Harrison, 2016/11/21 14:30:17]

It would be nice if we could keep a test like this in some form, maybe as a
browser test.

-  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();
-
-  web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl));
-  SimulateTimingUpdate(timing);
-  web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl2));
-  ASSERT_EQ(0, CountUpdatedTimingReported());
-  ASSERT_EQ(0, CountCompleteTimingReported());
-  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);
 
   web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
@@ skipping 258 matching lines @@
   web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl2));
   ASSERT_EQ(std::vector<GURL>({GURL(kDefaultTestUrl)}),
             completed_filtered_urls());
 
   web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl));
   ASSERT_EQ(std::vector<GURL>({GURL(kDefaultTestUrl), GURL(kDefaultTestUrl2)}),
             completed_filtered_urls());
 }
 
 }  // namespace page_load_metrics