WIP - not ready for review

Source/platform/ThreadTimers.h

Index: Source/platform/ThreadTimers.h
diff --git a/Source/platform/ThreadTimers.h b/Source/platform/ThreadTimers.h
index cba13bc3b940b1c3ff8bdae4dc7ec944a6f1533d..052df247969cb2e5f427923110e39f4e203622d2 100644
--- a/Source/platform/ThreadTimers.h
+++ b/Source/platform/ThreadTimers.h
@@ -28,6 +28,7 @@
 #define ThreadTimers_h
 
 #include "platform/PlatformExport.h"
+#include "platform/TimerHeap.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/HashSet.h"
 #include "wtf/Vector.h"
@@ -38,7 +39,7 @@ class SharedTimer;
 class TimerBase;
 
 // A collection of timers per thread. Kept in PlatformThreadData.
-class PLATFORM_EXPORT ThreadTimers {
+class PLATFORM_EXPORT ThreadTimers : public TimerQueueObserver {
     WTF_MAKE_NONCOPYABLE(ThreadTimers); WTF_MAKE_FAST_ALLOCATED;
 public:
     ThreadTimers();
@@ -46,7 +47,7 @@ public:
     // On a thread different then main, we should set the thread's instance of the SharedTimer.
     void setSharedTimer(SharedTimer*);
 
-    Vector<TimerBase*>& timerHeap() { return m_timerHeap; }
+    TimerHeap& timerHeap() { return m_timerHeap; }
 
     void updateSharedTimer();
     void fireTimersInNestedEventLoop();
@@ -54,10 +55,13 @@ public:
 private:
     static void sharedTimerFired();
 
+    // TimerQueueObserver
+    virtual void nextFiringTimerChanged() override;
+
     void sharedTimerFiredInternal();
     void fireTimersInNestedEventLoopInternal();
 
-    Vector<TimerBase*> m_timerHeap;
+    TimerHeap m_timerHeap;
     SharedTimer* m_sharedTimer; // External object, can be a run loop on a worker thread. Normally set/reset by worker thread.
     bool m_firingTimers; // Reentrancy guard.
     double m_pendingSharedTimerFireTime;