Clamp in VisualViewport::setScrollPosition.

third_party/WebKit/Source/core/frame/VisualViewport.cpp

 /*
  * Copyright (C) 2013 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 524 matching lines @@
 
 bool VisualViewport::shouldUseIntegerScrollOffset() const
 {
     LocalFrame* frame = mainFrame();
     if (frame && frame->settings() && !frame->settings()->preferCompositingToLCDTextEnabled())
         return true;
 
     return ScrollableArea::shouldUseIntegerScrollOffset();
 }
 
+void VisualViewport::setScrollPosition(const DoublePoint& scrollPoint, ScrollType scrollType, ScrollBehavior scrollBehavior)
+{
+    // We clamp the position here, because the ScrollAnimator may otherwise be
+    // set to a non-clamped position by ScrollableArea::setScrollPosition,
+    // which may lead to incorrect scrolling behavior in RootFrameViewport down
+    // the line.
+    // TODO(eseckler): Solve this instead by ensuring that ScrollableArea and
+    // ScrollAnimator are kept in sync. This requires that ScrollableArea always
+    // stores fractional offsets and that truncation happens elsewhere, see
+    // crbug.com/626315.
+    DoublePoint newScrollPosition = clampScrollPosition(scrollPoint);
+    ScrollableArea::setScrollPosition(newScrollPosition, scrollType, scrollBehavior);
+}
+
 int VisualViewport::scrollSize(ScrollbarOrientation orientation) const
 {
     IntSize scrollDimensions = maximumScrollPosition() - minimumScrollPosition();
     return (orientation == HorizontalScrollbar) ? scrollDimensions.width() : scrollDimensions.height();
 }
 
 IntPoint VisualViewport::minimumScrollPosition() const
 {
     return IntPoint();
 }
@@ skipping 277 matching lines @@
     } else if (graphicsLayer == m_rootTransformLayer.get()) {
         name =  "Root Transform Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink