Added PointerEvent firing on touch events.

Source/core/events/PointerEventUtils.cpp

Index: Source/core/events/PointerEventUtils.cpp
diff --git a/Source/core/events/PointerEventUtils.cpp b/Source/core/events/PointerEventUtils.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b078f6f52440b1cd464df9514d8b4f00eef54fd6
--- /dev/null
+++ b/Source/core/events/PointerEventUtils.cpp
@@ -0,0 +1,52 @@
+// 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.
+
+#include "config.h"
+#include "core/events/PointerEventUtils.h"
+
+namespace blink {
+
+PointerIdManager::PointerIdManager()
+{
+    clear();
+}
+
+PointerIdManager::~PointerIdManager()
+{
+    clear();
+}
+
+void PointerIdManager::clear()
+{
+    for (int type = 0; type < static_cast<int>(PointerTypeLastEntry); type++) {
+        m_ids[type].clear();
+        m_hasPrimaryId[type] = false;
+    }
+}
+
+void PointerIdManager::add(PointerType type, unsigned id)
+{
+    if (m_ids[type].isEmpty())
+        m_hasPrimaryId[type] = true;

[Rick Byers, 2015/06/16 17:25:39]

ASSERT(!m_hasPrimaryId[type]) ?

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

I relied on deduping-through-set here instead of an explicit assert because
apparently we have some tests violating unique id assumptions.

https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

[Rick Byers, 2015/06/18 17:40:07]

Oh right, clusterfuzz can definitely trigger this so we can't assert.  Ok, this
is fine - thanks.

[mustaq, 2015/06/18 18:20:53]

Acknowledged.

+    m_ids[type].add(id);
+}
+
+void PointerIdManager::remove(PointerType type, unsigned id)
+{
+    if (isPrimary(type, id)) {
+        m_ids[type].removeFirst();
+        m_hasPrimaryId[type] = false;

[Rick Byers, 2015/06/16 17:25:39]

ASSERT(m_hasPrimaryId[type]) ?

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

Ditto.

+    } else {
+        // Note that simply counting the number of ids instead of storing all of them is not enough.
+        // When id is absent, remove() should be a no-op.
+        m_ids[type].remove(id);
+    }
+}
+
+bool PointerIdManager::isPrimary(PointerType type, unsigned id)
+{
+    return m_hasPrimaryId[type] && m_ids[type].first() == id;
+}
+
+} // namespace blink