Don't include scroll offset in offsetFromLayoutObject for scrolling contents layers.

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

Index: third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
index 9081857db32c0caf9d08620a6d0a46f5ebc4eb72..6ddfb18ce348ef988f61d436ed403e8b8450e391 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
@@ -428,10 +428,12 @@ void LayoutBoxModelObject::setBackingNeedsPaintInvalidationInRect(const LayoutRe
             // Note: the subpixel accumulation of layer() does not need to be added here. It is already taken into account.
             squashingLayer->setNeedsDisplayInRect(enclosingIntRect(paintInvalidationRect), invalidationReason, object);
         }
+    } else if (paintInvalidationContainer.usesCompositedScrolling() && &paintInvalidationContainer != this) {
+        layer()->compositedLayerMapping()->setScrollingContentsNeedDisplayInRect(r, invalidationReason, object);
     } else {
+        // TODO(chrishtr): we should be able to skip scrolling content layers in this case.
         layer()->compositedLayerMapping()->setContentsNeedDisplayInRect(r, invalidationReason, object);
     }
-}

[Xianzhu, 2016/05/31 16:46:27]

?

[chrishtr, 2016/05/31 16:58:39]

Done.

 
 void LayoutBoxModelObject::invalidateDisplayItemClientOnBacking(const DisplayItemClient& displayItemClient, PaintInvalidationReason invalidationReason) const
 {