Use high precision timestamp for Event.timestamp

third_party/WebKit/Source/core/timing/PerformanceBase.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 404 matching lines @@
     }
 }
 
 // static
 double PerformanceBase::clampTimeResolution(double timeSeconds)
 {
     const double resolutionSeconds = 0.000005;
     return floor(timeSeconds / resolutionSeconds) * resolutionSeconds;
 }
 
-double PerformanceBase::now() const
+DOMHighResTimeStamp PerformanceBase::monotonicTimeToDOMHighResTimeStamp(double monotonicTime) const
 {
-    double nowSeconds = monotonicallyIncreasingTime() - m_timeOrigin;
-    return 1000.0 * clampTimeResolution(nowSeconds);
+    double timeInSeconds = monotonicTime - m_timeOrigin;
+    return convertSecondsToDOMHighResTimeStamp(clampTimeResolution(timeInSeconds));
+}
+
+DOMHighResTimeStamp PerformanceBase::now() const
+{
+    return monotonicTimeToDOMHighResTimeStamp(monotonicallyIncreasingTime()); // in milliseconds

[Rick Byers, 2015/09/29 15:57:59]

nit: this comment seems redundant (it's clear you're going to
DOMHighRestTimestamp - comments on units like this are necessary as a hack only
when using plain numeric types).

[majidvp, 2015/10/01 20:57:19]

Done.

 }
 
 DEFINE_TRACE(PerformanceBase)
 {
     visitor->trace(m_frameTimingBuffer);
     visitor->trace(m_resourceTimingBuffer);
     visitor->trace(m_userTiming);
     visitor->trace(m_observers);
     visitor->trace(m_activeObservers);
     visitor->trace(m_suspendedObservers);
     RefCountedGarbageCollectedEventTargetWithInlineData<PerformanceBase>::trace(visitor);
 }
 
 } // namespace blink