compositor-worker: Add mutable attributes to CompositorProxy.

Source/core/dom/CompositorProxy.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CompositorProxy_h
 #define CompositorProxy_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/dom/Element.h"
 #include "platform/heap/Handle.h"
@@ skipping 20 matching lines @@
         SCROLL_TOP  = 0x0002,
         TOUCH       = 0x0004,
         TRANSFORM   = 0x0008,
     };
 
     DEFINE_INLINE_TRACE() { }
 
     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
 
 #endif // CompositorProxy_h