compositor-worker: Introduce 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"
+#include "wtf/PassOwnPtr.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefCounted.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+class ExceptionState;
+class ExecutionContext;
+
+class CompositorProxy final : public GarbageCollectedFinalized<CompositorProxy>, public ScriptWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static CompositorProxy* create(ExecutionContext*, Element*, const Vector<String>& attributeArray, ExceptionState&);
+    static CompositorProxy* create(uint64_t element, uint32_t attributeFlags);
+    virtual ~CompositorProxy();
+
+    enum class Attributes {
+        NONE        = 0,
+        OPACITY     = 1 << 0,
+        SCROLL_LEFT = 1 << 2,
+        SCROLL_TOP  = 1 << 3,
+        TOUCH       = 1 << 4,
+        TRANSFORM   = 1 << 5,
+    };
+
+    DEFINE_INLINE_TRACE() { }
+
+    union AttributesBitfield {
+        AttributesBitfield(uint32_t flags) : m_flags(flags) { }
+        struct {
+            unsigned m_opacity : 1;
+            unsigned m_scrollLeft : 1;
+            unsigned m_scrollTop : 1;
+            unsigned m_touch : 1;
+            unsigned m_transform : 1;
+        } m_attributes;
+        uint32_t m_flags;
+    };
+
+    uint64_t elementId() const { return m_elementId; }
+    uint32_t bitfieldsSupported() const { return m_bitfieldsSupported.m_flags; }
+    bool supports(const String& attribute) const;
+
+protected:
+    CompositorProxy(Element&, const Vector<String>& attributeArray);
+    CompositorProxy(uint64_t element, uint32_t attributeFlags);
+
+private:
+    const uint64_t m_elementId;
+    const AttributesBitfield m_bitfieldsSupported;
+};
+
+} // namespace blink
+
+#endif // CompositorProxy_h