Oilpan: Add more trace events to platform/heap/

Source/platform/heap/ThreadState.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1024 matching lines @@
         , m_stats(stats)
     {
         m_threadState->registerSweepingTask();
     }
 
     virtual ~SweepNonFinalizedHeapTask()
     {
         m_threadState->unregisterSweepingTask();
     }
 
-    virtual void run() { m_heap->sweep(m_stats); }
+    virtual void run()
+    {
+        TRACE_EVENT0("blink_gc", "ThreadState::sweepNonFinalizedHeaps");
+        m_heap->sweep(m_stats);
+    }
 
 private:
     ThreadState* m_threadState;
     BaseHeap* m_heap;
     HeapStats* m_stats;
 };
 
 void ThreadState::performPendingSweep()
 {
     if (!sweepRequested())
@@ skipping 205 matching lines @@
             return gcInfo;
         }
     }
     if (needLockForIteration)
         threadAttachMutex().unlock();
     return 0;
 }
 #endif
 
 }