Cleaning up PointerIdManager and add id re-mapping

third_party/WebKit/Source/core/events/PointerIdManager.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 PointerIdManager_h
 #define PointerIdManager_h
 
 #include "public/platform/WebPointerProperties.h"
 #include "wtf/Allocator.h"
-#include "wtf/ListHashSet.h"
+#include "wtf/HashMap.h"
 
 namespace blink {
 
 /**
   Helper class for tracking the primary pointer id for each type of PointerEvents.
 */
 class PointerIdManager {
     DISALLOW_NEW();
 public:
+    typedef unsigned MappedId;
+    typedef std::pair<WebPointerProperties::PointerType, unsigned> GeneratedPointer;
+    static const MappedId s_invalidId;
     PointerIdManager();
     ~PointerIdManager();
     void clear();
-    void add(WebPointerProperties::PointerType, unsigned);
-    void remove(WebPointerProperties::PointerType, unsigned);
-    bool isPrimary(WebPointerProperties::PointerType, unsigned);
+    MappedId add(const GeneratedPointer);
+    void remove(const GeneratedPointer);
+    void remove(const MappedId);
+    bool isPrimary(const MappedId) const;
+    MappedId getPrimaryId(const WebPointerProperties::PointerType) const;
+    WebPointerProperties::PointerType getType(const MappedId) const;
 
 private:
-    // TODO(crbug.com/537319): Switch to /one/ set of ids to guarantee uniqueness.
-    ListHashSet<unsigned> m_ids[static_cast<int>(WebPointerProperties::PointerType::LastEntry) + 1];
-    bool m_hasPrimaryId[static_cast<int>(WebPointerProperties::PointerType::LastEntry) + 1];
+    HashMap<unsigned, MappedId> m_ids[static_cast<int>(WebPointerProperties::PointerType::LastEntry) + 1];
+    HashMap<MappedId, GeneratedPointer> m_reverseMapping;
+    MappedId m_primaryId[static_cast<int>(WebPointerProperties::PointerType::LastEntry) + 1];
 };
 
 } // namespace blink
 
 #endif // PointerIdManager_h