Move TopDocumentRootScrollerController to a separate object on FrameHost

third_party/WebKit/Source/core/page/scrolling/RootScrollerUtil.h

Index: third_party/WebKit/Source/core/page/scrolling/RootScrollerUtil.h
diff --git a/third_party/WebKit/Source/core/page/scrolling/RootScrollerUtil.h b/third_party/WebKit/Source/core/page/scrolling/RootScrollerUtil.h
new file mode 100644
index 0000000000000000000000000000000000000000..903fba0de4f1c13e7ed3d536af97a730af343d77
--- /dev/null
+++ b/third_party/WebKit/Source/core/page/scrolling/RootScrollerUtil.h
@@ -0,0 +1,21 @@
+// 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 RootScrollerUtil_h
+#define RootScrollerUtil_h
+
+namespace blink {
+
+class Element;
+class ScrollableArea;
+
+namespace RootScrollerUtil {
+
+ScrollableArea* scrollableAreaFor(const Element&);
+
+} // namespace RootScrollerUtil
+
+} // namespace blink
+
+#endif // RootScrollerUtil_h