Add WebPointerEvent, WebMouseProperties and WebPointerProperties types.

public/web/WebMouseProperties.h

+// Copyright (c) 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 WebMouseProperties_h
+#define WebMouseProperties_h
+
+namespace blink {
+
+// TODO(e_hakkinen): Replace WebTouchEvent with WebPointerEvent, remove
+//                   WebTouchEvent and WebTouchPoint and merge this into
+//                   WebMouseEvent.
+class WebMouseProperties {
+public:
+    WebMouseProperties()
+        : button(ButtonNone)
+    {
+    }
+
+    enum Button {
+        ButtonNone = -1,
+        ButtonLeft,
+        ButtonMiddle,
+        ButtonRight
+    };
+
+    Button button;
+};
+
+} // namespace blink
+
+#endif