[New Multicolumn] Support for paged overflow.

Source/core/rendering/RenderPagedFlowThread.h

Index: Source/core/rendering/RenderPagedFlowThread.h
diff --git a/Source/core/rendering/RenderPagedFlowThread.h b/Source/core/rendering/RenderPagedFlowThread.h
new file mode 100644
index 0000000000000000000000000000000000000000..fdc126e4b9cc7708ae614d71d55fff3e1340e49b
--- /dev/null
+++ b/Source/core/rendering/RenderPagedFlowThread.h
@@ -0,0 +1,32 @@
+// Copyright 2014 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 RenderPagedFlowThread_h
+#define RenderPagedFlowThread_h
+
+#include "core/rendering/RenderMultiColumnFlowThread.h"
+
+namespace WebCore {
+
+// A flow thread for paged overflow. FIXME: The current implementation relies on the multicol
+// implementation, but it in the long run it would be better to have what's common between
+// RenderMultiColumnFlowThread and RenderPagedFlowThread in RenderFlowThread, and have both of them
+// inherit from that one.
+class RenderPagedFlowThread : public RenderMultiColumnFlowThread {
+public:
+    static RenderPagedFlowThread* createAnonymous(Document&, RenderStyle* parentStyle);
+
+    RenderBlockFlow* pagedBlockFlow() const { return toRenderBlockFlow(parent()); }
+
+    virtual bool isRenderPagedFlowThread() const OVERRIDE { return true; }
+    virtual bool heightIsAuto() const OVERRIDE { return !columnHeightAvailable(); }
+    virtual const char* renderName() const OVERRIDE;
+    virtual bool needsNewWidth() const OVERRIDE;
+    virtual void updateLogicalWidth() OVERRIDE;
+    virtual void layout();
+};
+
+} // namespace WebCore
+
+#endif // RenderPagedFlowThread_h