[Page Load Metrics] PageLoadMetrics Mojofication.

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 682 matching lines @@
 
   NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
 
   blink::WebMouseEvent mouse_event(blink::WebInputEvent::kMouseDown,
                                    blink::WebInputEvent::kNoModifiers,
                                    blink::WebInputEvent::kTimeStampForTesting);
   SimulateInputEvent(mouse_event);
 
   timing.paint_timing.first_meaningful_paint =
-      base::TimeDelta::FromMilliseconds(1000);
+      base::TimeDelta::FromMilliseconds(1100);

[Zhen Wang, 2017/04/19 21:52:47]

Is there any reason to change this?

[lpy, 2017/04/20 01:49:24]

The overhead of SimulateTimingUpdate increases a little bit.

   PopulateRequiredTimingFields(&timing);
   SimulateTimingUpdate(timing);
 
   NavigateAndCommit(GURL(kDefaultTestUrl2));
 
   histogram_tester().ExpectTotalCount(
       internal::kHistogramFirstMeaningfulPaint, 0);
   histogram_tester().ExpectTotalCount(
       internal::kHistogramParseStartToFirstMeaningfulPaint, 0);
   histogram_tester().ExpectBucketCount(
       internal::kHistogramFirstMeaningfulPaintStatus,
       internal::FIRST_MEANINGFUL_PAINT_USER_INTERACTION_BEFORE_FMP, 1);
 }