Add LayoutObject::RarePaintData for rare paint data

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

Index: third_party/WebKit/Source/core/layout/LayoutObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.cpp b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
index 2ad2dafd5ad4efee4139334035aa2744f7f2ee39..77a4e3d57718b037499ec70e144e0487df158d69 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -126,7 +126,7 @@ struct SameSizeAsLayoutObject : DisplayItemClient {
   unsigned m_bitfields2;
   LayoutRect m_visualRect;
   LayoutPoint m_paintOffset;
-  std::unique_ptr<void*> m_paintProperties;
+  std::unique_ptr<void*> m_rarePaintData;
 };
 
 static_assert(sizeof(LayoutObject) == sizeof(SameSizeAsLayoutObject),
@@ -3552,16 +3552,20 @@ void LayoutObject::setIsBackgroundAttachmentFixedObject(
     frameView()->removeBackgroundAttachmentFixedObject(this);
 }
 
-const ObjectPaintProperties* LayoutObject::paintProperties() const {
-  DCHECK(RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled());
-  return m_paintProperties.get();
-}
+LayoutObject::RarePaintData::RarePaintData() {}

[Xianzhu, 2017/03/30 03:11:18]

Nit: I think we can just use the default constructor and constructor which are
inlined by default.

[pdr., 2017/03/30 18:57:33]

This does have to be here. Windows puts the default ctor in the header and we
don't have full type info for ObjectPaintProperties in the header.

The failure from commenting out this line is:
FAILED: blink_core.dll blink_core.dll.lib blink_core.dll.pdb
C:/python_27_amd64/files/python.exe ../../build/toolchain/win/tool_wrapper.py
link-wrapper environment.x86 False link.exe /nologo /IMPLIB:./blink_core.dll.lib
/DLL /OUT:./blin
k_core.dll /PDB:./blink_core.dll.pdb @./blink_core.dll.rsp
LayoutObject.obj : error LNK2019: unresolved external symbol "public: __thiscall
blink::LayoutObject::RarePaintData::RarePaintData(void)"
(??0RarePaintData@LayoutObject@blink@
@QAE@XZ) referenced in function "class std::unique_ptr<class
blink::LayoutObject::RarePaintData,struct std::default_delete<class
blink::LayoutObject::RarePaintData> > __cdecl
base::MakeUnique<class blink::LayoutObject::RarePaintData>(void)"
(??$MakeUnique@VRarePaintData@LayoutObject@blink@@$$V@base@@YA?AV?$unique_ptr@VRarePaintData@LayoutObject@bli
nk@@U?$default_delete@VRarePaintData@LayoutObject@blink@@@std@@@std@@XZ)
./blink_core.dll : fatal error LNK1120: 1 unresolved externals
ninja: build stopped: subcommand failed.

+
+LayoutObject::RarePaintData::~RarePaintData() {}
 
-ObjectPaintProperties& LayoutObject::ensurePaintProperties() {
-  DCHECK(RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled());
+ObjectPaintProperties& LayoutObject::RarePaintData::ensurePaintProperties() {
   if (!m_paintProperties)
     m_paintProperties = ObjectPaintProperties::create();
-  return *m_paintProperties;
+  return *m_paintProperties.get();
+}
+
+LayoutObject::RarePaintData& LayoutObject::ensureRarePaintData() {
+  if (!m_rarePaintData)
+    m_rarePaintData = WTF::makeUnique<RarePaintData>();
+  return *m_rarePaintData.get();
 }
 
 LayoutRect LayoutObject::debugRect() const {