Use monotonic time instead of current time in autoscroll controller

third_party/WebKit/Source/core/page/AutoscrollController.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * 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
@@ skipping 215 matching lines @@
     UseCounter::count(m_page->mainFrame(), UseCounter::PanScrollingStart);
     startAutoscroll();
 }
 #else
 bool AutoscrollController::panScrollInProgress() const
 {
     return false;
 }
 #endif
 
-// FIXME: This would get get better animation fidelity if it used the monotonicFrameBeginTime instead
-// of WTF::currentTime().
 void AutoscrollController::animate(double)
 {
     if (!m_autoscrollLayoutObject) {
         stopAutoscroll();
         return;
     }
 
     switch (m_autoscrollType) {
     case AutoscrollForDragAndDrop:
-        if (WTF::currentTime() - m_dragAndDropAutoscrollStartTime > autoscrollDelay)
+        if (WTF::monotonicallyIncreasingTime() - m_dragAndDropAutoscrollStartTime > autoscrollDelay)

[dtapuska, 2016/09/08 18:09:51]

You are going to have to adjust the initialization of the
m_dragAndDropAutoscrollStartTime because they are a different clock base (start
time).

[dtapuska, 2016/09/08 18:16:27]

Nevermind it appears that the m_dragAndDropAutoscrollStartTime is coming from
the event timestamp which is monotonic already.

             m_autoscrollLayoutObject->autoscroll(m_dragAndDropAutoscrollReferencePosition);
         break;
     case AutoscrollForSelection:
         if (LocalFrame* frame = m_autoscrollLayoutObject->frame()) {
             EventHandler& eventHandler = frame->eventHandler();
             if (!eventHandler.mousePressed()) {
                 stopAutoscroll();
                 return;
             }
             eventHandler.updateSelectionForMouseDrag();
@@ skipping 59 matching lines @@
         view->setCursor(eastPanningCursor());
     } else if (west) {
         view->setCursor(westPanningCursor());
     } else {
         view->setCursor(middlePanningCursor());
     }
 }
 #endif
 
 } // namespace blink