compositor-worker: Add mutable attributes to CompositorProxy.

Source/core/dom/CompositorProxy.h

Index: Source/core/dom/CompositorProxy.h
diff --git a/Source/core/dom/CompositorProxy.h b/Source/core/dom/CompositorProxy.h
index 7732c4c253983eb7f1b6e0673715e8ca0469fd4c..327dbbb7185ae6f67a1d5145e0ff427c1f438d12 100644
--- a/Source/core/dom/CompositorProxy.h
+++ b/Source/core/dom/CompositorProxy.h
@@ -38,15 +38,30 @@ public:
     static void notifyElementGone(Element*);
 
     uint64_t elementId() const { return m_elementId; }
-    uint32_t attributes() const { return m_attributes; }
+    uint32_t attributes() const { return m_mutableAttributes; }
+
+    double opacity(ExceptionState&) const;
+    double scrollTop(ExceptionState&) const;
+    Vector<double> transform(ExceptionState&) const;
+
+    void setOpacity(double, ExceptionState&);
+    void setScrollTop(double, ExceptionState&);
+    void setTransform(const Vector<double>&, ExceptionState&);
 
 protected:
     CompositorProxy(Element*, uint32_t attributeFlags);
     CompositorProxy(uint64_t element, uint32_t attributeFlags);
 
 private:
+    bool raiseExceptionIfNotMutable(Attributes, ExceptionState&) const;
+
     const uint64_t m_elementId;
-    uint32_t m_attributes;
+    uint32_t m_mutableAttributes;
+    uint32_t m_mutatedAttributes;

[esprehn, 2015/03/29 04:44:56]

Maybe use a bit field instead of the enum?

+
+    double m_opacity;
+    double m_scrollTop;
+    Vector<double, 16> m_transform;
 };
 
 } // namespace blink