Oilpan: Mark the NodeList hierarchy MainThreadOnly

Source/platform/heap/ThreadState.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 66 matching lines @@
 //
 // FIXME: We should evaluate the performance gain. Having
 // ThreadAffinity is complicating the implementation and we should get
 // rid of it if it is fast enough to go through thread-local storage
 // always.
 enum ThreadAffinity {
     AnyThread,
     MainThreadOnly,
 };
 
+// FIXME: These forward declarations violate dependency rules. Remove them.
+// Ideally we want to provide a USED_IN_MAIN_THREAD_ONLY(T) macro, which
+// indicates that classes in T's hierarchy are used only by the main thread.

[haraken, 2014/10/15 01:12:56]

I'm planning to address the FIXME by introducing GarbageCollectedOnMainThread in
a follow-up.

[tkent, 2014/10/15 03:34:39]

The GarbageCollectedOnMainThread approach sounds good.

 class Node;
-class CSSValue;
+class NodeList;
 
-template<typename T, bool derivesNode = WTF::IsSubclass<typename WTF::RemoveConst<T>::Type, Node>::value> struct DefaultThreadingTrait;
+template<typename T,
+    bool derivesNode = WTF::IsSubclass<typename WTF::RemoveConst<T>::Type, Node>::value

[tkent, 2014/10/15 03:34:39]

Now derivesNode is a wrong name.  It will be removed soon because of
GarbageCollectedOnMainThread, right?

[haraken, 2014/10/15 03:38:59]

Renamed it to mainThreadOnly.

+        || WTF::IsSubclass<typename WTF::RemoveConst<T>::Type, NodeList>::value> struct DefaultThreadingTrait;
 
 template<typename T>
 struct DefaultThreadingTrait<T, false> {
     static const ThreadAffinity Affinity = AnyThread;
 };
 
 template<typename T>
 struct DefaultThreadingTrait<T, true> {
     static const ThreadAffinity Affinity = MainThreadOnly;
 };
@@ skipping 814 matching lines @@
     // whether the page is part of a terminting thread or
     // if the page is traced after being terminated (orphaned).
     uintptr_t m_terminating : 1;
     uintptr_t m_tracedAfterOrphaned : 1;
     uintptr_t m_promptlyFreedSize : 17; // == blinkPageSizeLog2
 };
 
 }
 
 #endif // ThreadState_h