Oilpan: persist Timer<T>'s object while active.

Source/platform/Timer.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 384 matching lines @@
 }
 
 void TimerBase::fireTimersInNestedEventLoop()
 {
     // Redirect to ThreadTimers.
     PlatformThreadData::current().threadTimers().fireTimersInNestedEventLoop();
 }
 
 void TimerBase::didChangeAlignmentInterval()
 {
-    setNextFireTime(m_unalignedNextFireTime);
+    this->setNextFireTime(m_unalignedNextFireTime);
 }
 
 double TimerBase::nextUnalignedFireInterval() const
 {
     ASSERT(isActive());
     return std::max(m_unalignedNextFireTime - monotonicallyIncreasingTime(), 0.0);
 }
 
+namespace {
+
+class ActiveTimerInstanceTracker final : public GarbageCollectedFinalized<ActiveTimerInstanceTracker> {
+public:
+    void add(const void* self, TimerInstanceTracker::TraceMethodTrampoline trampoline)
+    {
+        m_activeTimerInstances.add(self, trampoline);
+    }
+
+    void remove(const void* self)
+    {
+        m_activeTimerInstances.remove(self);
+    }
+
+    void trace(Visitor* visitor)
+    {
+        for (const auto& active : m_activeTimerInstances)
+            active.value(visitor, const_cast<void*>(active.key));
+    }
+
+private:
+    using ActiveTimerInstanceMap = HashMap<const void*, TimerInstanceTracker::TraceMethodTrampoline>;
+
+    ActiveTimerInstanceMap m_activeTimerInstances;
+};
+
+static ActiveTimerInstanceTracker& activeTimerInstanceTracker()
+{
+    DEFINE_STATIC_LOCAL(Persistent<ActiveTimerInstanceTracker>, tracker, (new ActiveTimerInstanceTracker));
+    return *tracker;
+}
+
+}
+
+void TimerInstanceTracker::add(const void* self, TraceMethodTrampoline trampoline)
+{
+    ActiveTimerInstanceTracker& tracker = activeTimerInstanceTracker();
+    tracker.add(self, trampoline);
+}
+
+void TimerInstanceTracker::remove(const void* self)
+{
+    ActiveTimerInstanceTracker& tracker = activeTimerInstanceTracker();
+    tracker.remove(self);
+}
+
 } // namespace blink