Cleaning up PointerIdManager and add id re-mapping

third_party/WebKit/Source/core/events/PointerIdManager.cpp

Index: third_party/WebKit/Source/core/events/PointerIdManager.cpp
diff --git a/third_party/WebKit/Source/core/events/PointerIdManager.cpp b/third_party/WebKit/Source/core/events/PointerIdManager.cpp
index a0342b72387e5550842a64cd8307099dc0d7523b..b355b764a96bd50b5d9a2e883e030a7bf2f5f4b4 100644
--- a/third_party/WebKit/Source/core/events/PointerIdManager.cpp
+++ b/third_party/WebKit/Source/core/events/PointerIdManager.cpp
@@ -10,10 +10,15 @@ namespace blink {
 namespace {
 
 inline int toInt(WebPointerProperties::PointerType t) { return static_cast<int>(t); }
+// Mouse id is 1 to behave the same as MS Edge for compatibility reasons.
+const PointerIdManager::MappedId mouseId = 1;
 
 } // namespace
 
+const PointerIdManager::MappedId PointerIdManager::s_invalidId = 0;
+
 PointerIdManager::PointerIdManager()
+: m_currentId(2)
 {
     clear();
 }
@@ -27,32 +32,81 @@ void PointerIdManager::clear()
 {
     for (int type = 0; type <= toInt(WebPointerProperties::PointerType::LastEntry); type++) {
         m_ids[type].clear();
-        m_hasPrimaryId[type] = false;
+        m_primaryId[type] = PointerIdManager::s_invalidId;
     }
+    m_reverseMapping.clear();
+
+    // Always add mouse pointer in initialization and never remove it.
+    // No need to add it to m_ids as it is not going to be used with the existing APIs
+    m_primaryId[toInt(WebPointerProperties::PointerType::Mouse)] = mouseId;
+    m_reverseMapping.add(mouseId, GeneratedPointer(WebPointerProperties::PointerType::Mouse, 0));
 }
 
-void PointerIdManager::add(WebPointerProperties::PointerType type, unsigned id)
+PointerIdManager::MappedId PointerIdManager::add(const GeneratedPointer p)
 {
-    if (m_ids[toInt(type)].isEmpty())
-        m_hasPrimaryId[toInt(type)] = true;
-    m_ids[toInt(type)].add(id);
+    // Do not add extra mouse pointer as it was added in initialization
+    if (p.first == WebPointerProperties::PointerType::Mouse)
+        return mouseId;
+
+    int type = toInt(p.first);
+    unsigned id = p.second;
+    if (m_ids[type].contains(id))
+        return m_ids[type].get(id);
+    // We do not handle the overflow of m_currentId as it should be very rare
+    MappedId mappedId = m_currentId++;
+    if (m_ids[type].isEmpty())
+        m_primaryId[type] = mappedId;
+    m_ids[type].add(id, mappedId);
+    m_reverseMapping.add(mappedId, p);
+    return static_cast<PointerIdManager::MappedId>(mappedId);
 }
 
-void PointerIdManager::remove(WebPointerProperties::PointerType type, unsigned id)
+void PointerIdManager::remove(const GeneratedPointer p)
 {
-    if (isPrimary(type, id)) {
-        m_ids[toInt(type)].removeFirst();
-        m_hasPrimaryId[toInt(type)] = false;
-    } 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[toInt(type)].remove(id);
-    }
+    int type = toInt(p.first);
+    unsigned id = p.second;
+    if (!m_ids[type].contains(id))
+        return;
+    remove(m_ids[type].get(id));
 }
 
-bool PointerIdManager::isPrimary(WebPointerProperties::PointerType type, unsigned id)
+void PointerIdManager::remove(const PointerIdManager::MappedId mappedId)
 {
-    return m_hasPrimaryId[toInt(type)] && m_ids[toInt(type)].first() == id;
+    // Do not remove mouse pointer id as it should always be there
+    if (mappedId == mouseId || !m_reverseMapping.contains(mappedId))
+        return;
+
+    GeneratedPointer p = m_reverseMapping.get(mappedId);
+    int type = toInt(p.first);
+    unsigned id = p.second;
+    m_reverseMapping.remove(mappedId);
+    m_ids[type].remove(id);
+    if (m_primaryId[type] == mappedId)
+        m_primaryId[type] = PointerIdManager::s_invalidId;
+}
+
+bool PointerIdManager::isPrimary(PointerIdManager::MappedId mappedId) const
+{
+    if (!m_reverseMapping.contains(mappedId))
+        return false;
+
+    GeneratedPointer p = m_reverseMapping.get(mappedId);
+    int type = toInt(p.first);
+    return m_primaryId[type] == mappedId;
 }
 
+PointerIdManager::MappedId PointerIdManager::getPrimaryId(const WebPointerProperties::PointerType type) const
+{
+    return m_primaryId[toInt(type)];
+}
+
+WebPointerProperties::PointerType PointerIdManager::getType(const PointerIdManager::MappedId mappedId) const
+{
+    if (!m_reverseMapping.contains(mappedId))
+        return WebPointerProperties::PointerType::Unknown;
+
+    return m_reverseMapping.get(mappedId).first;
+}
+
+
 } // namespace blink