Let synchronized painting generate correct paint invalidation rects

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

Index: third_party/WebKit/Source/core/paint/PaintLayer.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.cpp b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
index 94ca11eb5669da1ec0491ae13997b17c1625dd2c..e8e14a06d1b99c64b4d51902c06081894823cfc3 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -2693,7 +2693,7 @@ void PaintLayer::markAncestorChainForNeedsRepaint()
     // Need to access compositingState(). We've ensured correct flag setting when compositingState() changes.
     DisableCompositingQueryAsserts disabler;
 
-    if (compositingState() != NotComposited)
+    if (compositingState() == PaintsIntoOwnBacking)

[chrishtr, 2015/10/22 00:02:41]

Not squashing?

[Xianzhu, 2015/10/22 01:17:04]

We need to mark needsRepaint until real GraphicsLayers because we issue
CachedDisplayItemList according to the needsRepaint flag of the root layer of a
real GraphicsLayer.

[chrishtr, 2015/10/23 17:15:06]

Then you need to stop at squashing layers and mark the owningLayer of the CLM
which has the squashing layer as needsRepaint.

[Xianzhu, 2015/10/23 18:43:27]

I realized this too :) Fixed in the patch set 7.

         return;
 
     PaintLayer* layer = this;
@@ -2710,7 +2710,7 @@ void PaintLayer::markAncestorChainForNeedsRepaint()
                 break;
             container->m_needsRepaint = true;
         }
-        if (container->compositingState() != NotComposited)
+        if (container->compositingState() == PaintsIntoOwnBacking)
             break;
         layer = container;
     }