[Prerender] first contentful paint histograms.

chrome/browser/prerender/prerender_test_utils.h

 // Copyright (c) 2016 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.
 
 #ifndef CHROME_BROWSER_PRERENDER_PRERENDER_TEST_UTILS_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_TEST_UTILS_H_
 
 #include <deque>
 #include <functional>
 #include <memory>
 #include <set>
 #include <string>
 #include <unordered_map>
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "base/run_loop.h"
 #include "base/test/histogram_tester.h"
 #include "chrome/browser/external_protocol/external_protocol_handler.h"
+#include "chrome/browser/page_load_metrics/observers/prerender_page_load_metrics_observer.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/safe_browsing/test_safe_browsing_service.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "components/safe_browsing_db/test_database_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/test/url_request/url_request_mock_http_job.h"
 #include "net/url_request/url_request_interceptor.h"
 #include "url/gurl.h"
 
@@ skipping 200 matching lines @@
   void MarkDestruction(FinalStatus reason);
 
   base::RunLoop wait_loop_;
   FinalStatus expected_final_status_;
   bool saw_correct_status_;
   std::unique_ptr<DestructionMarker> marker_;
 
   DISALLOW_COPY_AND_ASSIGN(DestructionWaiter);
 };
 
+// Wait until a PrerenderManager has seen a first contentful paint.
+class FirstContentfulPaintManagerWaiter : public PrerenderManagerObserver {
+ public:
+  // Create and return a pointer to a |FirstContentfulPaintManagerWaiter|. The
+  // instance is owned by the |PrerenderManager|.
+  static FirstContentfulPaintManagerWaiter* Create(PrerenderManager* manager);
+
+  ~FirstContentfulPaintManagerWaiter() override;
+
+  void OnFirstContentfulPaint() override;
+
+  // Wait for a first contentful paint to be seen by our PrerenderManager.
+  void Wait();
+
+ private:
+  FirstContentfulPaintManagerWaiter();
+
+  std::unique_ptr<base::RunLoop> waiter_;
+  bool saw_fcp_;
+};

[pasko, 2016/12/20 19:33:34]

nit: DISALLOW_COPY_AND_ASSIGN?

[mattcary, 2016/12/21 17:08:58]

Done.

+
 // PrerenderContentsFactory that uses TestPrerenderContents.
 class TestPrerenderContentsFactory : public PrerenderContents::Factory {
  public:
   TestPrerenderContentsFactory();
 
   ~TestPrerenderContentsFactory() override;
 
   std::unique_ptr<TestPrerender> ExpectPrerenderContents(
       FinalStatus final_status);
 
@@ skipping 106 matching lines @@
       safe_browsing_factory_;
   TestPrerenderContentsFactory* prerender_contents_factory_;
   Browser* explicitly_set_browser_;
   bool autostart_test_server_;
   base::HistogramTester histogram_tester_;
   std::unique_ptr<net::EmbeddedTestServer> https_src_server_;
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderInProcessBrowserTest);
 };
 
+// A test observer that allows the observed navigation start time to be set.
+class TestPrerenderPageLoadMetricsObserver
+    : public PrerenderPageLoadMetricsObserver {
+ public:
+  using PrerenderPageLoadMetricsObserver::PrerenderPageLoadMetricsObserver;

[pasko, 2016/12/20 19:33:34]

thanks for letting me know about inherited constructors :)

[mattcary, 2016/12/21 17:08:58]

Ack

I think it was actually from digit@ and notes from his C++ class...

+
+  void SetNavigationStartTo(base::TimeTicks ticks) {
+    SetNavigationStartTicksForTesting(ticks);

[pasko, 2016/12/20 19:33:34]

The only thing this class does is forwarding to this protected method, which
complicates reading the callsites. Can we make
PrerenderPageLoadMetricsObserver::SetNavigationStartTicksForTesting() public
instead?

[mattcary, 2016/12/21 17:08:59]

It seems to be common to hide testing code with protected, but it doesn't matter
much to me.

[pasko, 2016/12/21 18:39:09]

Ah, now I see where it is coming from. I think it is an important feature of the
suffix "ForTesting" to avoid extra overhead of subclassing.

[mattcary, 2016/12/22 10:49:07]

Acknowledged.

+  }
+};

[pasko, 2016/12/20 19:33:34]

nit: DISALLOW_COPY_AND_ASSIGN?

[mattcary, 2016/12/21 17:08:59]

Done.

+
 // Makes |url| respond to requests with the contents of |file|, counting the
 // number that start in |counter|.
 void CreateCountingInterceptorOnIO(
     const GURL& url,
     const base::FilePath& file,
     const base::WeakPtr<RequestCounter>& counter);
 
 // When the |url| hits the net::URLRequestFilter (on the IO thread), executes
 // the |callback_io| providing the request to it, also pings the |counter| on UI
 // thread. Does not modify the behavior or the request job.
 void InterceptRequestAndCount(
     const GURL& url,
     RequestCounter* counter,
     base::Callback<void(net::URLRequest*)> callback_io);
 
 // Makes |url| respond to requests with the contents of |file|.
 void CreateMockInterceptorOnIO(const GURL& url, const base::FilePath& file);
 
 // Makes |url| never respond on the first load, and then with the contents of
 // |file| afterwards. When the first load has been scheduled, runs |callback| on
 // the UI thread.
 void CreateHangingFirstRequestInterceptorOnIO(
     const GURL& url, const base::FilePath& file, base::Closure callback);
 
 }  // namespace test_utils
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_TEST_UTILS_H_