Added PointerEvent firing on touch events.

Source/core/events/PointerEventUtils.h

+// 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 PointerEventUtils_h

[Rick Byers, 2015/06/16 17:25:38]

Do you have plans to add other "utils" here?  Usually our filenames match the
class name (I know some editor workflows expect that).  Maybe just call this
PointerIdManager.* for now?

[mustaq, 2015/06/16 20:18:42]

Done.

+#define PointerEventUtils_h
+
+#include "wtf/ListHashSet.h"
+
+namespace blink {
+
+/**
+  Helps tracking the primary pointer id for PointerEvents.
+*/
+class PointerIdManager {
+public:
+    PointerIdManager();
+    ~PointerIdManager();
+    void clear();
+    void add(unsigned);
+    void remove(unsigned);
+    bool isPrimary(unsigned);
+
+private:
+    // TODO(mustaq): Add per-type state when we have support for non-touch PointerEvents.
+    ListHashSet<unsigned> m_ids;
+    bool m_hasPrimaryId;
+};
+
+} // namespace blink
+
+#endif // PointerEventUtils_h