Plumb selection bounds as a single unit

public/web/WebSelection.h

Index: public/web/WebSelection.h
diff --git a/public/web/WebSelection.h b/public/web/WebSelection.h
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+++ b/public/web/WebSelection.h
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+// 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 WebSelection_h
+#define WebSelection_h
+
+#include "../platform/WebCommon.h"
+#include "../platform/WebSelectionBound.h"
+
+namespace blink {
+
+struct CompositedSelection;
+
+// The active selection region, containing compositing data for the selection
+// end points as well as metadata for the selection region.
+class BLINK_EXPORT WebSelection {
+public:
+    enum SelectionType { NoSelection, CaretSelection, RangeSelection };
+
+#if INSIDE_BLINK
+    explicit WebSelection(const CompositedSelection&);
+#endif
+    WebSelection(const WebSelection&);
+
+    const WebSelectionBound& base() const { return m_base; }
+    const WebSelectionBound& extent() const { return m_extent; }
+    const WebSelectionBound& start() const { return isBaseFirst() ? base() : extent(); }
+    const WebSelectionBound& end() const { return isBaseFirst() ? extent() : base(); }
+
+    bool isNone() const { return selectionType() == NoSelection; }
+    bool isCaret() const { return selectionType() == CaretSelection; }
+    bool isRange() const { return selectionType() == RangeSelection; }
+
+    bool isBaseFirst() const { return m_isBaseFirst; }
+    bool isEditable() const { return m_isEditable; }
+    bool isEditableRegionEmpty() const { return m_isEditableRegionEmpty; }
+
+private:
+    SelectionType selectionType() const { return m_selectionType; }
+
+    SelectionType m_selectionType;
+
+    WebSelectionBound m_base;
+    WebSelectionBound m_extent;
+
+    // Whether |m_base| comes before |m_extent| in document position order.
+    bool m_isBaseFirst;
+
+    // Whether the selection region consists of editable text.
+    bool m_isEditable;
+
+    // If the selection region is editable text, whether it is empty.
+    bool m_isEditableRegionEmpty;
+};
+
+} // namespace blink
+
+#endif // WebSelection_h