Assert event timestamp to be monotonic and not from future

third_party/WebKit/Source/core/events/Event.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 12 matching lines @@
 #include "core/events/Event.h"
 
 #include "core/dom/StaticNodeList.h"
 #include "core/events/EventDispatchMediator.h"
 #include "core/events/EventTarget.h"
 #include "core/frame/HostsUsingFeatures.h"
 #include "core/frame/UseCounter.h"
 #include "core/svg/SVGElement.h"
 #include "core/timing/DOMWindowPerformance.h"
 #include "core/timing/Performance.h"
+#include "platform/Histogram.h"
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
 static bool isEventTypeScopedInV0(const AtomicString& eventType)
 {
     // WebKit never allowed selectstart event to cross the the shadow DOM boundary.
     // Changing this breaks existing sites.
     // See https://bugs.webkit.org/show_bug.cgi?id=52195 for details.
     return eventType == EventTypeNames::abort
@@ skipping 10 matching lines @@
 
 Event::Event()
     : Event("", false, false)
 {
     m_wasInitialized = false;
 }
 
 Event::Event(const AtomicString& eventType, bool canBubbleArg, bool cancelableArg, double platformTimeStamp)
     : Event(eventType, canBubbleArg, cancelableArg, ComposedMode::Scoped, platformTimeStamp)
 {
+    // Verify that timestamp is coming from the monotonic clock.
+    double delta = monotonicallyIncreasingTime() - platformTimeStamp;
+    bool hasValidTimebase = delta >= 0 && delta <= 60 * 1000;
+
+    DEFINE_STATIC_LOCAL(BooleanHistogram, histogram, ("Event.TimestampHasValidTimebase.Renderer"));
+    histogram.count(hasValidTimebase);
+    DCHECK(hasValidTimebase);
 }
 
 Event::Event(const AtomicString& eventType, bool canBubbleArg, bool cancelableArg, ComposedMode composedMode)
     : Event(eventType, canBubbleArg, cancelableArg, composedMode, monotonicallyIncreasingTime())
 {
 }
 
 Event::Event(const AtomicString& eventType, bool canBubbleArg, bool cancelableArg, ComposedMode composedMode, double platformTimeStamp)
     : m_type(eventType)
     , m_canBubble(canBubbleArg)
@@ skipping 293 matching lines @@
 
 DEFINE_TRACE(Event)
 {
     visitor->trace(m_currentTarget);
     visitor->trace(m_target);
     visitor->trace(m_underlyingEvent);
     visitor->trace(m_eventPath);
 }
 
 } // namespace blink