Refactor BlendMode into a separate class.

Source/core/rendering/RenderLayerBlendInfo.h

+/*
+ * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
+ * Copyright (C) 2013 Intel Corporation. All rights reserved.
+ *
+ * Portions are Copyright (C) 1998 Netscape Communications Corporation.
+ *
+ * Other contributors:
+ *   Robert O'Callahan <roc+@cs.cmu.edu>
+ *   David Baron <dbaron@fas.harvard.edu>
+ *   Christian Biesinger <cbiesinger@web.de>
+ *   Randall Jesup <rjesup@wgate.com>
+ *   Roland Mainz <roland.mainz@informatik.med.uni-giessen.de>
+ *   Josh Soref <timeless@mac.com>
+ *   Boris Zbarsky <bzbarsky@mit.edu>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Alternatively, the contents of this file may be used under the terms
+ * of either the Mozilla Public License Version 1.1, found at
+ * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
+ * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
+ * (the "GPL"), in which case the provisions of the MPL or the GPL are
+ * applicable instead of those above.  If you wish to allow use of your
+ * version of this file only under the terms of one of those two
+ * licenses (the MPL or the GPL) and not to allow others to use your
+ * version of this file under the LGPL, indicate your decision by
+ * deletingthe provisions above and replace them with the notice and
+ * other provisions required by the MPL or the GPL, as the case may be.
+ * If you do not delete the provisions above, a recipient may use your
+ * version of this file under any of the LGPL, the MPL or the GPL.
+ */
+
+#ifndef RenderLayerBlendInfo_h
+#define RenderLayerBlendInfo_h
+
+#include "public/platform/WebBlendMode.h"
+#include "wtf/Assertions.h"
+#include "wtf/Noncopyable.h"
+
+namespace WebCore {
+
+class RenderLayerModelObject;
+
+class RenderLayerBlendInfo {
+    WTF_MAKE_NONCOPYABLE(RenderLayerBlendInfo);
+public:
+    explicit RenderLayerBlendInfo(RenderLayerModelObject*);
+
+    bool hasBlendMode() const;
+    void updateBlendMode();
+
+    bool childLayerHasBlendMode() const
+    {
+        ASSERT(!m_childLayerHasBlendModeStatusDirty);
+        return m_childLayerHasBlendMode;
+    }
+    bool childLayerHasBlendModeWhileDirty() const { return m_childLayerHasBlendMode; }
+
+    void setChildLayerHasBlendMode(bool b) { m_childLayerHasBlendMode = b; }
+
+    bool childLayerHasBlendModeStatusDirty() const { return m_childLayerHasBlendModeStatusDirty; }
+    void setChildLayerHasBlendModeStatusDirty(bool b) { m_childLayerHasBlendModeStatusDirty = b; }
+
+    void setAncestorChainBlendedDescendant();
+    void dirtyAncestorChainBlendedDescendantStatus();
+
+    blink::WebBlendMode blendMode() const { return m_blendMode; }
+
+private:
+    RenderLayerModelObject* m_renderer;
+    blink::WebBlendMode m_blendMode;
+
+    unsigned m_childLayerHasBlendMode : 1;
+    unsigned m_childLayerHasBlendModeStatusDirty : 1;
+};
+
+} // namespace WebCore
+
+#endif // RenderLayerBlendInfo_h