Added DCHECK for monotonicTimeToDOMHighResTimeStamp in PerformanceBase

third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp

 // Copyright 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.
 
 #include "core/paint/FirstMeaningfulPaintDetector.h"
 
 #include "core/paint/PaintTiming.h"
 #include "core/testing/DummyPageHolder.h"
+#include "core/timing/DOMWindowPerformance.h"
+#include "core/timing/Performance.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 
 class FirstMeaningfulPaintDetectorTest : public testing::Test {
  protected:
   void SetUp() override {
     m_dummyPageHolder = DummyPageHolder::create(IntSize(800, 600));
-    s_timeElapsed = 0.0;
+    s_timeElapsed = timeOrigin();
     m_originalTimeFunction = setTimeFunctionsForTesting(returnMockTime);
   }
 
   void TearDown() override {
     setTimeFunctionsForTesting(m_originalTimeFunction);
   }
 
   Document& document() { return m_dummyPageHolder->document(); }
   PaintTiming& paintTiming() { return PaintTiming::from(document()); }
+  
   FirstMeaningfulPaintDetector& detector() {
     return paintTiming().firstMeaningfulPaintDetector();
   }
 
   void simulateLayoutAndPaint(int newElements) {
     StringBuilder builder;
     for (int i = 0; i < newElements; i++)
       builder.append("<span>a</span>");
     document().write(builder.toString());
     document().updateStyleAndLayout();
     detector().notifyPaint();
   }
 
   void simulateNetworkStable() { detector().networkStableTimerFired(nullptr); }
 
  private:
   static double returnMockTime() {
     s_timeElapsed += 1.0;
     return s_timeElapsed;
   }
 
+  double timeOrigin() {

[panicker, 2017/01/13 19:11:59]

Update CL description mentioning why this file is updated.

[sunjian, 2017/01/13 19:49:33]

Done.

+    Performance* performance = DOMWindowPerformance::performance(*m_dummyPageHolder->frame().domWindow());

[panicker, 2017/01/13 19:11:59]

Nit: did you run git cl format?

[sunjian, 2017/01/13 19:49:33]

Done.

+    if (!performance)
+      return 0.0;
+    return performance->timeOrigin();
+  }
+
   std::unique_ptr<DummyPageHolder> m_dummyPageHolder;
   TimeFunction m_originalTimeFunction;
   static double s_timeElapsed;
 };
 
 double FirstMeaningfulPaintDetectorTest::s_timeElapsed;
 
 TEST_F(FirstMeaningfulPaintDetectorTest, NoFirstPaint) {
   simulateLayoutAndPaint(1);
   simulateNetworkStable();
@@ skipping 52 matching lines @@
   paintTiming().markFirstPaint();
   simulateLayoutAndPaint(1);
   simulateNetworkStable();
   EXPECT_EQ(paintTiming().firstMeaningfulPaint(), 0.0);
   paintTiming().markFirstContentfulPaint();
   simulateNetworkStable();
   EXPECT_NE(paintTiming().firstMeaningfulPaint(), 0.0);
 }
 
 }  // namespace blink