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..b74ebd51e6e85a0b5faef621ae5f58a2e8ccd56b 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)
@@ -471,6 +472,13 @@ public:
         Parent::operator=(other);
         return *this;
     }
+
+    template<typename U>
+    static CrossThreadPersistent<U> protectWeak(const PersistentBase<U, WeakPersistentConfiguration, CrossThreadPersistentConfiguration>& other)

[haraken, 2016/09/12 11:45:09]

Can we drop the changes in this file?

+    {
+        CrossThreadPersistentRegion::LockScope persistentLock(ProcessHeap::crossThreadPersistentRegion());
+        return CrossThreadPersistent<U>(other.getInternal());
+    }
 };
 
 // Combines the behavior of CrossThreadPersistent and WeakPersistent.
@@ -520,6 +528,32 @@ public:
         Parent::operator=(other);
         return *this;
     }
+
+    T& operator*() const

[haraken, 2016/09/12 11:45:09]

As discussed offline, we should try to remove CrossThreadWeakPersistent instead
of making it more powerful.

[keishi, 2016/09/13 03:12:42]

Sorry. Done.

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