Refactor scroll updates during flexbox layout.

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

Index: third_party/WebKit/Source/core/layout/LayoutDeprecatedFlexibleBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutDeprecatedFlexibleBox.cpp b/third_party/WebKit/Source/core/layout/LayoutDeprecatedFlexibleBox.cpp
index ed3942e2c946921f27add396f22f623c55659e18..35cbeb7358df2349ebf767ee8c4dd8887536bc06 100644
--- a/third_party/WebKit/Source/core/layout/LayoutDeprecatedFlexibleBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutDeprecatedFlexibleBox.cpp
@@ -309,7 +309,7 @@ void LayoutDeprecatedFlexibleBox::layoutHorizontalBox(bool relayoutChildren)
     bool haveFlex = false, flexingChildren = false;
     gatherFlexChildrenInfo(iterator, relayoutChildren, highestFlexGroup, lowestFlexGroup, haveFlex);
 
-    LayoutBlock::startDelayUpdateScrollInfo();
+    PaintLayerScrollableArea::DelayScrollPositionClampScope delayClampScope;

[leviw_travelin_and_unemployed, 2016/04/28 22:50:04]

Grumble grumble DeprecatedFlexBox :(

We have tests that cover this? I'm not hugely concerned about it, but I wonder.

[szager1, 2016/05/12 20:44:50]

I have no idea, and I'm not sure I should give a care.

[cbiesinger, 2016/05/13 19:52:48]

Yeah I wouldn't worry about this

 
     // We do 2 passes.  The first pass is simply to lay everyone out at
     // their preferred widths.  The second pass handles flexing the children.
@@ -532,8 +532,6 @@ void LayoutDeprecatedFlexibleBox::layoutHorizontalBox(bool relayoutChildren)
         }
     } while (haveFlex);
 
-    LayoutBlock::finishDelayUpdateScrollInfo(nullptr, nullptr);
-
     if (remainingSpace > 0 && ((style()->isLeftToRightDirection() && style()->boxPack() != Start)
         || (!style()->isLeftToRightDirection() && style()->boxPack() != End))) {
         // Children must be repositioned.
@@ -609,7 +607,7 @@ void LayoutDeprecatedFlexibleBox::layoutVerticalBox(bool relayoutChildren)
     if (haveLineClamp)
         applyLineClamp(iterator, relayoutChildren);
 
-    LayoutBlock::startDelayUpdateScrollInfo();
+    PaintLayerScrollableArea::DelayScrollPositionClampScope delayClampScope;
 
     // We do 2 passes.  The first pass is simply to lay everyone out at
     // their preferred widths.  The second pass handles flexing the children.
@@ -783,8 +781,6 @@ void LayoutDeprecatedFlexibleBox::layoutVerticalBox(bool relayoutChildren)
         }
     } while (haveFlex);
 
-    LayoutBlock::finishDelayUpdateScrollInfo(nullptr, nullptr);
-
     if (style()->boxPack() != Start && remainingSpace > 0) {
         // Children must be repositioned.
         LayoutUnit offset;