Use high precision timestamp for Event.timestamp

third_party/WebKit/Source/core/testing/Internals.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 2523 matching lines @@
         return false;
 
     return animator->setScrollbarsVisibleForTesting(visible);
 }
 
 void Internals::forceRestrictIFramePermissions()
 {
     RuntimeEnabledFeatures::setRestrictIFramePermissionsEnabled(true);
 }
 
+double Internals::monotonicTimeToZeroBasedDocumentTime(double platformTime, ExceptionState& exceptionState)
+{
+    Document* document = contextDocument();
+    if (!document) {
+        exceptionState.throwDOMException(InvalidAccessError, "No context document is available.");
+        return 0;
+    }
+
+    return document->monotonicTimeToZeroBasedDocumentTime(platformTime);
+}
+
 } // namespace blink