Skip paint offset caching when DisplayItemList is skipping cache

third_party/WebKit/Source/core/paint/BlockPainter.cpp

Index: third_party/WebKit/Source/core/paint/BlockPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/BlockPainter.cpp b/third_party/WebKit/Source/core/paint/BlockPainter.cpp
index 35459944fbb7b7dbd0b37d0dfbac5c3bee82edfc..2b80cc07a51af1e9ac4fce65a2911692d266150e 100644
--- a/third_party/WebKit/Source/core/paint/BlockPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/BlockPainter.cpp
@@ -143,7 +143,7 @@ void BlockPainter::paintAsInlineBlock(const LayoutObject& layoutObject, const Pa
 
 void BlockPainter::paintObject(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
-    if (RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() && m_layoutBlock.childrenInline()) {
+    if (RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() && m_layoutBlock.childrenInline() && !paintInfo.context->displayItemList()->skippingCache()) {

[pdr., 2015/10/06 03:10:25]

WDYT about renaming skippingCache to skippingCacheAndPaintOffsetChecks()? I
think it's likely we will forget that skipping the cache also skips the paint
offset code.

We could then update the setPreviousPaintOffset calls to
ASSERT(!skippingCacheAndPaintOffsetChecks());

[Xianzhu, 2015/10/06 16:35:23]

I think paint offset cache is also a cache that skip-cache should skip :) 
I'd like LayoutObject no to know such details of DisplayItemList. The current
DisplayItemList::invalidatePaintOffset() assertions are enough to discover such
issues.

         if (m_layoutBlock.paintOffsetChanged(paintOffset)) {
             LineBoxListPainter(m_layoutBlock.lineBoxes()).invalidateLineBoxPaintOffsets(paintInfo);
             paintInfo.context->displayItemList()->invalidatePaintOffset(m_layoutBlock);