Remove LayoutBlockFlow overflow invalidation

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

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index a7c3fbaa3f3f668b9194863b73863c28d45eef99..8872d9016e7e66048e593dad232b9c7db6ef8038 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -58,7 +58,6 @@ bool LayoutBlockFlow::s_canPropagateFloatIntoSibling = false;
 
 struct SameSizeAsLayoutBlockFlow : public LayoutBlock {
     LineBoxList lineBoxes;
-    LayoutUnit m_paintInvalidationLogicalTopAndBottom[2];
     void* pointers[2];
 };
 
@@ -397,17 +396,6 @@ void LayoutBlockFlow::layoutBlock(bool relayoutChildren)
 
     updateAfterLayout();
 
-    if (m_paintInvalidationLogicalTop != m_paintInvalidationLogicalBottom) {
-        bool hasVisibleContent = style()->visibility() == VISIBLE;
-        if (!hasVisibleContent) {
-            PaintLayer* layer = enclosingLayer();
-            layer->updateDescendantDependentFlags();
-            hasVisibleContent = layer->hasVisibleContent();
-        }
-        if (hasVisibleContent)
-            setShouldInvalidateOverflowForPaint();
-    }
-
     if (isHTMLDialogElement(node()) && isOutOfFlowPositioned())
         positionDialog();
 
@@ -467,8 +455,6 @@ inline bool LayoutBlockFlow::layoutBlockFlow(bool relayoutChildren, LayoutUnit &
     LayoutUnit previousHeight = logicalHeight();
     setLogicalHeight(beforeEdge);
 
-    m_paintInvalidationLogicalTop = LayoutUnit();
-    m_paintInvalidationLogicalBottom = LayoutUnit();
     if (!firstChild() && !isAnonymousBlock())
         setChildrenInline(true);
 
@@ -480,7 +466,7 @@ inline bool LayoutBlockFlow::layoutBlockFlow(bool relayoutChildren, LayoutUnit &
     // all inline children are removed from this block.
     setContainsInlineWithOutlineAndContinuation(false);
     if (childrenInline())
-        layoutInlineChildren(relayoutChildren, m_paintInvalidationLogicalTop, m_paintInvalidationLogicalBottom, afterEdge);
+        layoutInlineChildren(relayoutChildren, afterEdge);
     else
         layoutBlockChildren(relayoutChildren, layoutScope, beforeEdge, afterEdge);
 
@@ -2789,48 +2775,6 @@ void LayoutBlockFlow::invalidatePaintForOverhangingFloats(bool paintAllDescendan
     }
 }
 
-void LayoutBlockFlow::invalidatePaintForOverflow()

[chrishtr, 2016/06/27 15:12:42]

Does the version control history give a hint as to which use cases this code was
optimizing?

[Xianzhu, 2016/06/27 17:05:19]

This was to avoid full inalidation of LayoutBlockFlow with inline contents when
not all of the lines are changed during layout. This was needed before
paint-invalidation-after-layout when we didn't invalidate LayoutInlines and
LayoutTexts and let LayoutBlockFlow handle all paint invalidation of changed
line layout.

Actually I hadn't know how and why of this before several weeks ago, and didn't
mention this in the paint invalidation documentation in
Source/core/paint/README.md.

This is also hard to handle in SPv2 paint invalidation because we'll use visual
rects of display items.

-{
-    // FIXME: We could tighten up the left and right invalidation points if we let layoutInlineChildren fill them in based off the particular lines
-    // it had to lay out. We wouldn't need the hasOverflowClip() hack in that case either.
-    LayoutUnit paintInvalidationLogicalLeft = logicalLeftVisualOverflow();
-    LayoutUnit paintInvalidationLogicalRight = logicalRightVisualOverflow();
-    if (hasOverflowClip()) {
-        // If we have clipped overflow, we should use layout overflow as well, since visual overflow from lines didn't propagate to our block's overflow.
-        // Note the old code did this as well but even for overflow:visible. The addition of hasOverflowClip() at least tightens up the hack a bit.
-        // layoutInlineChildren should be patched to compute the entire paint invalidation rect.
-        paintInvalidationLogicalLeft = std::min(paintInvalidationLogicalLeft, logicalLeftLayoutOverflow());
-        paintInvalidationLogicalRight = std::max(paintInvalidationLogicalRight, logicalRightLayoutOverflow());
-    }
-
-    LayoutRect paintInvalidationRect;
-    if (isHorizontalWritingMode())
-        paintInvalidationRect = LayoutRect(paintInvalidationLogicalLeft, m_paintInvalidationLogicalTop, paintInvalidationLogicalRight - paintInvalidationLogicalLeft, m_paintInvalidationLogicalBottom - m_paintInvalidationLogicalTop);
-    else
-        paintInvalidationRect = LayoutRect(m_paintInvalidationLogicalTop, paintInvalidationLogicalLeft, m_paintInvalidationLogicalBottom - m_paintInvalidationLogicalTop, paintInvalidationLogicalRight - paintInvalidationLogicalLeft);
-
-    if (hasOverflowClip()) {
-        // Adjust the paint invalidation rect for scroll offset
-        paintInvalidationRect.move(-scrolledContentOffset());
-
-        // Don't allow this rect to spill out of our overflow box.
-        paintInvalidationRect.intersect(LayoutRect(LayoutPoint(), size()));
-    }
-
-    // Make sure the rect is still non-empty after intersecting for overflow above
-    if (!paintInvalidationRect.isEmpty()) {
-        // Hits in media/event-attributes.html
-        DisableCompositingQueryAsserts disabler;
-
-        invalidatePaintRectangle(paintInvalidationRect); // We need to do a partial paint invalidation of our content.
-        if (hasReflection())
-            invalidatePaintRectangle(reflectedRect(paintInvalidationRect));
-    }
-
-    m_paintInvalidationLogicalTop = LayoutUnit();
-    m_paintInvalidationLogicalBottom = LayoutUnit();
-}
-
 void LayoutBlockFlow::invalidateDisplayItemClients(PaintInvalidationReason invalidationReason) const
 {
     LayoutBlock::invalidateDisplayItemClients(invalidationReason);