Make compositingState explicit

Source/core/rendering/CompositingState.h

+// Copyright 2013 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 CompositingState_h
+#define CompositingState_h
+
+namespace WebCore {
+
+enum CompositingState {
+    // The layer paints into its enclosing composited ancestor.
+    NotComposited = 0,
+
+    // The layer is composited, but its contents still paint into enclosing composited ancestor.
+    // In this state, repaint invalidations must be sent to the enclosing composited ancestor.
+    // Typically this happens when a layer's properties need to be represented in the compositor
+    // output data structures, but it doesn't actually have any other reasons to be composited.
+    HasOwnBackingButPaintsIntoAncestor = 1,
+
+    PaintsIntoOwnBacking = 2,
+};
+
+} // namespace WebCore
+
+#endif // CompositingState_h