Oilpan: Count # of collected Persistent handles and use it to estimate the live object size

Source/platform/heap/ThreadState.h

Index: Source/platform/heap/ThreadState.h
diff --git a/Source/platform/heap/ThreadState.h b/Source/platform/heap/ThreadState.h
index a5e834dd14f3c3e4c3282eae56cfdac53eefac0f..57cd0461b91eb51deaf415cfe897993089c77560 100644
--- a/Source/platform/heap/ThreadState.h
+++ b/Source/platform/heap/ThreadState.h
@@ -479,10 +479,22 @@ public:
 
     // A region of PersistentNodes allocated on the given thread.
     PersistentRegion* persistentRegion() const { return m_persistentRegion.get(); }
-
     // A region of PersistentNodes not owned by any particular thread.
     static CrossThreadPersistentRegion& crossThreadPersistentRegion();
 
+    // TODO(haraken): Currently CrossThreadPersistent handles are not counted.
+    // This wouldn't be a big deal because # of CrossThreadPersistents is small,
+    // but should be fixed.
+    void persistentAllocated()
+    {
+        ++m_persistentAllocated;
+    }
+    void persistentFreed()
+    {
+        ++m_persistentFreed;
+    }
+    void updatePersistentCounters();
+
     // Visit local thread stack and trace all pointers conservatively.
     void visitStack(Visitor*);
 
@@ -679,6 +691,8 @@ private:
     // Internal helper for GC policy handling code. Returns true if
     // an urgent conservative GC is now needed due to memory pressure.
     bool shouldForceMemoryPressureGC();
+    size_t estimatedLiveObjectSize();
+    size_t currentObjectSize();
 
     void runScheduledGC(StackState);
 
@@ -738,6 +752,8 @@ private:
     bool m_sweepForbidden;
     size_t m_noAllocationCount;
     size_t m_gcForbiddenCount;
+    int m_persistentAllocated;
+    int m_persistentFreed;
     BaseHeap* m_heaps[NumberOfHeaps];
 
     int m_vectorBackingHeapIndex;