Cleanups of PaintController

third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
index 60a818a51d108c4e1a2b17c304a2459d7c73b17f..055ec8df442bff0f3ade57a1c2526d0fac957418 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
@@ -737,7 +737,11 @@ String PaintController::displayItemListAsDebugString(const DisplayItemList& list
 
 void PaintController::showDebugDataInternal(bool showPictures) const
 {
+    // In NDEBUG mode we call DisplayItemClient::debugName() in displayItemListAsDebugString() which can only be called
+    // when we are sure the client is still alive. It's not suitable for m_currentPaintArtifact.getDisplayItemList().
+#ifndef NDEBUG

[pdr., 2016/09/12 19:45:07]

I'd prefer if this function didn't work completely differently depending on
ndebug. Is there a way to check for liveness in displayItemListAsDebugString in
ndebug mode and still print the rest of the information? If not, could we just
delete the m_currentPaintArtifact part?

[Xianzhu, 2016/09/12 20:54:49]

We can't enable liveness checking in release build because it's expensive.
The m_currentPaintArtifact is important for debugging the merge algorithm.

In the new patch set, I changed PaintController::displayItemListAsDebugString()
instead of PaintController::showDebugDataInternal() to minimize the differences
between release and debug builds.

     WTFLogAlways("current display item list: [%s]\n", displayItemListAsDebugString(m_currentPaintArtifact.getDisplayItemList(), showPictures).utf8().data());
+#endif
     WTFLogAlways("new display item list: [%s]\n", displayItemListAsDebugString(m_newDisplayItemList, showPictures).utf8().data());
 }