Revert of Refactor ScrollableArea::setScrollPosition.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 515cacad14698660e7c442b3bbd0d9c8a45405f9..196a2f1d2316777b0f2d53fe467703e35735e793 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -263,22 +263,18 @@
   }
 
   // If our zoom factor changes and we have a defined scrollLeft/Top, we need to
-  // adjust that value into the new zoomed coordinate space.  Note that the new
-  // scroll position may be outside the normal min/max range of the scrollable
-  // area, which is weird but OK, because the scrollable area will update its
-  // min/max in updateAfterLayout().
+  // adjust that value into the new zoomed coordinate space.
   if (hasOverflowClip() && oldStyle &&
       oldStyle->effectiveZoom() != newStyle.effectiveZoom()) {
     PaintLayerScrollableArea* scrollableArea = this->getScrollableArea();
     ASSERT(scrollableArea);
-    // We use scrollPosition() rather than adjustedScrollPosition(), because
-    // scrollPosition is the distance from the beginning of flow for the box,
-    // which is the dimension we want to preserve.
-    DoublePoint oldPosition = scrollableArea->scrollPositionDouble();
-    if (oldPosition.x() || oldPosition.y()) {
-      DoublePoint newPosition = oldPosition.scaledBy(newStyle.effectiveZoom() /
-                                                     oldStyle->effectiveZoom());
-      scrollableArea->setScrollPositionUnconditionally(newPosition);
+    if (int left = scrollableArea->scrollXOffset()) {
+      left = (left / oldStyle->effectiveZoom()) * newStyle.effectiveZoom();
+      scrollableArea->scrollToXOffset(left);
+    }
+    if (int top = scrollableArea->scrollYOffset()) {
+      top = (top / oldStyle->effectiveZoom()) * newStyle.effectiveZoom();
+      scrollableArea->scrollToYOffset(top);
     }
   }
 
@@ -526,15 +522,13 @@
 }
 
 LayoutUnit LayoutBox::scrollLeft() const {
-  return hasOverflowClip()
-             ? LayoutUnit(getScrollableArea()->adjustedScrollOffset().width())
-             : LayoutUnit();
+  return hasOverflowClip() ? LayoutUnit(getScrollableArea()->scrollXOffset())
+                           : LayoutUnit();
 }
 
 LayoutUnit LayoutBox::scrollTop() const {
-  return hasOverflowClip()
-             ? LayoutUnit(getScrollableArea()->adjustedScrollOffset().height())
-             : LayoutUnit();
+  return hasOverflowClip() ? LayoutUnit(getScrollableArea()->scrollYOffset())
+                           : LayoutUnit();
 }
 
 int LayoutBox::pixelSnappedScrollWidth() const {
@@ -555,12 +549,9 @@
   // setScrollTop does, presumably this code does as well.
   DisableCompositingQueryAsserts disabler;
 
-  if (hasOverflowClip()) {
-    PaintLayerScrollableArea* scrollableArea = getScrollableArea();
-    scrollableArea->scrollToOffset(
-        DoubleSize(newLeft, scrollableArea->adjustedScrollOffset().height()),
-        ScrollBehaviorAuto);
-  }
+  if (hasOverflowClip())
+    getScrollableArea()->scrollToXOffset(newLeft, ScrollOffsetClamped,
+                                         ScrollBehaviorAuto);
 }
 
 void LayoutBox::setScrollTop(LayoutUnit newTop) {
@@ -568,12 +559,9 @@
   // compositing/overflow/do-not-assert-on-invisible-composited-layers.html
   DisableCompositingQueryAsserts disabler;
 
-  if (hasOverflowClip()) {
-    PaintLayerScrollableArea* scrollableArea = getScrollableArea();
-    scrollableArea->scrollToOffset(
-        DoubleSize(scrollableArea->adjustedScrollOffset().width(), newTop),
-        ScrollBehaviorAuto);
-  }
+  if (hasOverflowClip())
+    getScrollableArea()->scrollToYOffset(newTop, ScrollOffsetClamped,
+                                         ScrollBehaviorAuto);
 }
 
 void LayoutBox::scrollToOffset(const DoubleSize& offset,
@@ -583,7 +571,8 @@
   DisableCompositingQueryAsserts disabler;
 
   if (hasOverflowClip())
-    getScrollableArea()->scrollToOffset(offset, scrollBehavior);
+    getScrollableArea()->scrollToOffset(offset, ScrollOffsetClamped,
+                                        scrollBehavior);
 }
 
 // Returns true iff we are attempting an autoscroll inside an iframe with
@@ -1104,7 +1093,8 @@
   scroll(ScrollByPixel, FloatSize(adjustedScrollDelta(delta)));
 }
 
-void LayoutBox::scrollByRecursively(const DoubleSize& delta) {
+void LayoutBox::scrollByRecursively(const DoubleSize& delta,
+                                    ScrollOffsetClamping clamp) {
   if (delta.isZero())
     return;
 
@@ -1117,7 +1107,7 @@
     ASSERT(scrollableArea);
 
     DoubleSize newScrollOffset = scrollableArea->adjustedScrollOffset() + delta;
-    scrollableArea->scrollToOffset(newScrollOffset);
+    scrollableArea->scrollToOffset(newScrollOffset, clamp);
 
     // If this layer can't do the scroll we ask the next layer up that can
     // scroll to try.
@@ -1125,7 +1115,7 @@
         newScrollOffset - scrollableArea->adjustedScrollOffset();
     if (!remainingScrollOffset.isZero() && parent()) {
       if (LayoutBox* scrollableBox = enclosingScrollableBox())
-        scrollableBox->scrollByRecursively(remainingScrollOffset);
+        scrollableBox->scrollByRecursively(remainingScrollOffset, clamp);
 
       LocalFrame* frame = this->frame();
       if (frame && frame->page())