Use monotonic time instead of current time in autoscroll controller

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

Index: third_party/WebKit/Source/core/page/AutoscrollController.cpp
diff --git a/third_party/WebKit/Source/core/page/AutoscrollController.cpp b/third_party/WebKit/Source/core/page/AutoscrollController.cpp
index 0934143858f7592725af5e51b1c6fdde30aaa720..8acd36cb410057bfbf3ed01cc2219fe4e09718e6 100644
--- a/third_party/WebKit/Source/core/page/AutoscrollController.cpp
+++ b/third_party/WebKit/Source/core/page/AutoscrollController.cpp
@@ -233,8 +233,6 @@ bool AutoscrollController::panScrollInProgress() const
 }
 #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) {
@@ -244,7 +242,7 @@ void AutoscrollController::animate(double)
 
     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: