Prepare CompositorWorker for per thread heap

third_party/WebKit/Source/platform/heap/Persistent.h

Index: third_party/WebKit/Source/platform/heap/Persistent.h
diff --git a/third_party/WebKit/Source/platform/heap/Persistent.h b/third_party/WebKit/Source/platform/heap/Persistent.h
index 37399f545ca475db1e18cd29ce91cdf00fed7e81..6f73be4ae67993c3285773afb90d6bd23539de64 100644
--- a/third_party/WebKit/Source/platform/heap/Persistent.h
+++ b/third_party/WebKit/Source/platform/heap/Persistent.h
@@ -114,6 +114,7 @@ public:
     operator T*() const { return m_raw; }
     T* operator->() const { return *this; }
     T* get() const { return m_raw; }
+    T* getInternal() const { return m_raw; }
 
     template<typename U>
     PersistentBase& operator=(U* other)
@@ -437,8 +438,6 @@ public:
     CrossThreadPersistent(const Member<U>& other) : Parent(other) { }
     CrossThreadPersistent(WTF::HashTableDeletedValueType x) : Parent(x) { }
 
-    T* atomicGet() { return Parent::atomicGet(); }
-
     template<typename U>
     CrossThreadPersistent& operator=(U* other)
     {
@@ -471,6 +470,13 @@ public:
         Parent::operator=(other);
         return *this;
     }
+
+    template<typename U>
+    static CrossThreadPersistent<U> protectWeak(const PersistentBase<U, WeakPersistentConfiguration, CrossThreadPersistentConfiguration>& other)
+    {
+        CrossThreadPersistentRegion::LockScope persistentLock(ProcessHeap::crossThreadPersistentRegion());
+        return CrossThreadPersistent<U>(other.getInternal());
+    }
 };
 
 // Combines the behavior of CrossThreadPersistent and WeakPersistent.
@@ -520,6 +526,34 @@ public:
         Parent::operator=(other);
         return *this;
     }
+
+    T* atomicGet() { return Parent::atomicGet(); }
+
+    T& operator*() const
+    {
+        DCHECK(!Parent::get() || !ThreadState::current() || !ThreadState::current()->perThreadHeapEnabled() || &ThreadState::fromObject(Parent::get())->heap() == &ThreadState::current()->heap());

[haraken, 2016/09/02 09:39:18]

Should we drop the '|| !ThreadState::current()->perThreadHeapEnabled()' part?

It's unsafe to let a thread use a CrossThreadWeakPersistent even if the
per-thread heap is not enabled on *this* thread (i.e., it's unsafe if the
per-thread heap is enabled on a GCing thread).

[keishi, 2016/09/07 10:14:42]

Done.

+        return Parent::operator*();
+    }
+    explicit operator bool() const
+    {
+        DCHECK(!Parent::get() || !ThreadState::current() || !ThreadState::current()->perThreadHeapEnabled() || &ThreadState::fromObject(Parent::get())->heap() == &ThreadState::current()->heap());
+        return Parent::operator bool();
+    }
+    operator T*() const
+    {
+        DCHECK(!Parent::get() || !ThreadState::current() || !ThreadState::current()->perThreadHeapEnabled() || &ThreadState::fromObject(Parent::get())->heap() == &ThreadState::current()->heap());
+        return Parent::operator T*();
+    }
+    T* operator->() const
+    {
+        DCHECK(!Parent::get() || !ThreadState::current() || !ThreadState::current()->perThreadHeapEnabled() || &ThreadState::fromObject(Parent::get())->heap() == &ThreadState::current()->heap());
+        return Parent::operator->();
+    }
+    T* get() const
+    {
+        DCHECK(!Parent::get() || !ThreadState::current() || !ThreadState::current()->perThreadHeapEnabled() || &ThreadState::fromObject(Parent::get())->heap() == &ThreadState::current()->heap());
+        return Parent::get();
+    }
 };
 
 template<typename Collection>