Refactor ScrollableArea::setScrollPosition.

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
index c2506d5401a4a1841e96e1dbba5957325c013a08..82484a831d496118a4087a73fda62b14b3536b09 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -178,22 +178,28 @@ ScrollResult ScrollableArea::userScroll(ScrollGranularity granularity,
 void ScrollableArea::setScrollPosition(const DoublePoint& position,
                                        ScrollType scrollType,
                                        ScrollBehavior behavior) {
+  DoublePoint clampedPosition = clampScrollPosition(position);
+  if (shouldUseIntegerScrollOffset())
+    clampedPosition = flooredIntPoint(clampedPosition);
+  if (clampedPosition == scrollPositionDouble())
+    return;
+
   if (behavior == ScrollBehaviorAuto)
     behavior = scrollBehaviorStyle();
 
   switch (scrollType) {
     case CompositorScroll:
-      scrollPositionChanged(clampScrollPosition(position), scrollType);
+      scrollPositionChanged(clampedPosition, scrollType);
       break;
     case AnchoringScroll:
-      scrollAnimator().adjustAnimationAndSetScrollPosition(position,
+      scrollAnimator().adjustAnimationAndSetScrollPosition(clampedPosition,

[bokan, 2016/10/01 20:32:47]

I think you can remove the clamps in
ScrollAnimator::adjustAnimationAndSetScrollPosition and
ScrollAnimatorCompositorCoordinator::adjustAnimationAndSetScrollPosition.

[szager1, 2016/10/02 19:35:28]

Done.

                                                            scrollType);
       break;
     case ProgrammaticScroll:
-      programmaticScrollHelper(position, behavior);
+      programmaticScrollHelper(clampedPosition, behavior);
       break;
     case UserScroll:
-      userScrollHelper(position, behavior);
+      userScrollHelper(clampedPosition, behavior);
       break;
     default:
       ASSERT_NOT_REACHED();
@@ -271,7 +277,7 @@ void ScrollableArea::scrollPositionChanged(const DoublePoint& position,
       shouldUseIntegerScrollOffset() ? flooredIntPoint(position) : position;
 
   // Tell the derived class to scroll its contents.
-  setScrollOffset(truncatedPosition, scrollType);
+  updateScrollPosition(truncatedPosition, scrollType);
 
   // Tell the scrollbars to update their thumb postions.
   // If the scrollbar does not have its own layer, it must always be
@@ -306,8 +312,9 @@ bool ScrollableArea::scrollBehaviorFromString(const String& behaviorString,
 }
 
 // NOTE: Only called from Internals for testing.
-void ScrollableArea::setScrollOffsetFromInternals(const IntPoint& offset) {
-  scrollPositionChanged(DoublePoint(offset), ProgrammaticScroll);
+void ScrollableArea::updateScrollPositionFromInternals(
+    const IntPoint& position) {
+  scrollPositionChanged(DoublePoint(position), ProgrammaticScroll);
 }
 
 void ScrollableArea::contentAreaWillPaint() const {