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 d1afa53078370852b7b5a27d26e213afc004d24a..e3d5379025e9a07f8bebc5200a9d8151e157470c 100644
--- a/Source/core/dom/CompositorProxy.h
+++ b/Source/core/dom/CompositorProxy.h
@@ -6,6 +6,7 @@
 #define CompositorProxy_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/DOMMatrix.h"
 #include "core/dom/Element.h"
 #include "platform/heap/Handle.h"
 #include "wtf/PassOwnPtr.h"
@@ -15,6 +16,7 @@
 
 namespace blink {
 
+class DOMMatrix;
 class ExceptionState;
 class ExecutionContext;
 
@@ -28,25 +30,46 @@ public:
     enum class Attributes {
         NONE        = 0,
         OPACITY     = 1 << 0,
-        SCROLL_LEFT = 1 << 2,
-        SCROLL_TOP  = 1 << 3,
-        TOUCH       = 1 << 4,
-        TRANSFORM   = 1 << 5,
+        SCROLL_LEFT = 1 << 1,
+        SCROLL_TOP  = 1 << 2,
+        TOUCH       = 1 << 3,
+        TRANSFORM   = 1 << 4,
     };
 
-    DEFINE_INLINE_TRACE() { }
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(m_transform);
+    }
 
     uint64_t elementId() const { return m_elementId; }
     uint32_t bitfieldsSupported() const { return m_bitfieldsSupported; }
     bool supports(const String& attribute) const;
 
+    double opacity(ExceptionState&) const;
+    double scrollLeft(ExceptionState&) const;
+    double scrollTop(ExceptionState&) const;
+    DOMMatrix* transform(ExceptionState&) const;
+
+    void setOpacity(double, ExceptionState&);
+    void setScrollLeft(double, ExceptionState&);
+    void setScrollTop(double, ExceptionState&);
+    void setTransform(DOMMatrix*, ExceptionState&);
+
 protected:
     CompositorProxy(Element&, const Vector<String>& attributeArray);
     CompositorProxy(uint64_t element, uint32_t attributeFlags);
 
 private:
-    const uint64_t m_elementId;
-    const uint32_t m_bitfieldsSupported;
+    bool raiseExceptionIfNotMutable(Attributes, ExceptionState&) const;
+
+    const uint64_t m_elementId = 0;
+    const uint32_t m_bitfieldsSupported = 0;
+    uint32_t m_mutatedAttributes = 0;
+
+    double m_opacity = 0;
+    double m_scrollLeft = 0;
+    double m_scrollTop = 0;
+    Member<DOMMatrix> m_transform;
 };
 
 } // namespace blink