[Oilpan] Add HeapObjectHeader::gcGeneration() and related methods

third_party/WebKit/Source/platform/heap/HeapPage.cpp

Index: third_party/WebKit/Source/platform/heap/HeapPage.cpp
diff --git a/third_party/WebKit/Source/platform/heap/HeapPage.cpp b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
index 4ee87f0fea6c2adb3cd7e0bde17424874351f4d6..660c7c790eb8b4ec090f79727ddaa01a6157e75e 100644
--- a/third_party/WebKit/Source/platform/heap/HeapPage.cpp
+++ b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
@@ -95,6 +95,16 @@ void HeapObjectHeader::zapMagic()
     ASSERT(checkHeader());
     m_magic = zappedMagic;
 }
+
+void HeapObjectHeader::putGcGeneration()
+{
+    m_gcGeneration = Heap::gcGeneration();
+}
+
+void HeapObjectHeader::clearGcGeneration()
+{
+    m_gcGeneration = 0;
+}
 #endif
 
 void HeapObjectHeader::finalize(Address object, size_t objectSize)