Add experimental support for tracing the state of the VM heap to a file

src/heap.h

Index: src/heap.h
===================================================================
--- src/heap.h	(revision 9457)
+++ src/heap.h	(working copy)
@@ -919,7 +919,7 @@
 
   // Code that should be run before and after each GC.  Includes some
   // reporting/verification activities when compiled with DEBUG set.
-  void GarbageCollectionPrologue();
+  void GarbageCollectionPrologue(GarbageCollector collector);
   void GarbageCollectionEpilogue();
 
   // Performs garbage collection operation.
@@ -1455,6 +1455,22 @@
   // around a GC).
   inline void CompletelyClearInstanceofCache();
 
+  // Heap visualizer support.
+  bool has_visualizer() { return visualizer_ != NULL; }
+  HeapVisualizer* visualizer() { return visualizer_; }
+  void set_visualizer(HeapVisualizer* that) {
+    visualizer_ = that;
+  }
+  void UpdateVisualizers(Page* page);
+  void UpdateVisualizer(HeapVisualizer* visualizer);
+  void VisualizeCrankshaft();  // Entering Crankshaft optimizer.
+  void VisualizeCrankshaftDone();  // Exiting Crankshaft optimizer.
+  void UpdateHeapVisualizer(HeapVisualizer* visualizer, NewSpace* space);
+  void UpdateHeapVisualizer(HeapVisualizer* visualizer, PagedSpace* space);
+  void UpdateHeapVisualizer(HeapVisualizer* visualizer,
+                            LargeObjectSpace* space);
+  void VisualizerTimeStamp(HeapVisualizer::ProfileState);
+
  private:
   Heap();
 
@@ -1479,6 +1495,8 @@
   int always_allocate_scope_depth_;
   int linear_allocation_scope_depth_;
 
+  HeapVisualizer* visualizer_;
+
   // For keeping track of context disposals.
   int contexts_disposed_;