Introduce DocumentOrShadowRoot Mixin

third_party/WebKit/Source/core/dom/DocumentOrShadowRoot.h

+// Copyright 2016 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 DocumentOrShadowRoot_h
+#define DocumentOrShadowRoot_h
+
+#include "core/dom/Document.h"
+#include "core/dom/shadow/ShadowRoot.h"
+
+namespace blink {
+
+class DocumentOrShadowRoot {
+public:
+    static Element* activeElement(Document& document)
+    {
+        return document.activeElement();

[kochi, 2016/03/22 03:43:56]

Can activeElement() and styleSheets() be a pure virtual function for
TreeScope(),
and override in Document and ShadowRoot, then call it as
treeScope.activeElement()
like getSelection() below?

[hayato, 2016/03/22 03:50:08]

I did not do it intentionally in this CL. That should be done in another CL.

+    }
+
+    static Element* activeElement(ShadowRoot& shadowRoot)
+    {
+        return shadowRoot.activeElement();
+    }
+
+    static StyleSheetList* styleSheets(Document& document)
+    {
+        return document.styleSheets();
+    }
+
+    static StyleSheetList* styleSheets(ShadowRoot& shadowRoot)
+    {
+        return shadowRoot.styleSheets();
+    }
+
+    static DOMSelection* getSelection(TreeScope& treeScope)
+    {
+        return treeScope.getSelection();
+    }
+
+    static Element* elementFromPoint(TreeScope& treeScope, int x, int y)
+    {
+        return treeScope.elementFromPoint(x, y);
+    }
+
+    static WillBeHeapVector<RawPtrWillBeMember<Element>> elementsFromPoint(TreeScope& treeScope, int x, int y)
+    {
+        return treeScope.elementsFromPoint(x, y);
+    }
+};
+
+} // namespace blink
+
+#endif // DocumentOrShadowRoot_h