Object ID Ring with tests

runtime/vm/heap.h

Index: runtime/vm/heap.h
diff --git a/runtime/vm/heap.h b/runtime/vm/heap.h
index 359efeae2766c7302df49f6e4123f7fa11925a25..690e621891a80b52e549abb6b8fef361af7c5188 100644
--- a/runtime/vm/heap.h
+++ b/runtime/vm/heap.h
@@ -196,6 +196,19 @@ class Heap {
     return size <= kNewAllocatableSize;
   }
 
+  void set_object_id_ring_table(RawObject** object_id_ring_table,
+                                intptr_t object_id_ring_table_size) {
+    ASSERT(!gc_in_progress_);
+    object_id_ring_table_ = object_id_ring_table;
+    object_id_ring_table_size_ = object_id_ring_table_size;
+  }
+  RawObject** get_object_id_ring_table() {
+    return object_id_ring_table_;
+  }
+  intptr_t get_object_id_ring_table_size() {
+    return object_id_ring_table_size_;
+  }
+
  private:
   class GCStats : public ValueObject {
    public:
@@ -255,6 +268,10 @@ class Heap {
   // GC on the heap is in progress.
   bool gc_in_progress_;
 
+  // Ring of objects who have a vm service id assigned to them.
+  RawObject** object_id_ring_table_;
+  intptr_t object_id_ring_table_size_;
+
   friend class GCTestHelper;
   DISALLOW_COPY_AND_ASSIGN(Heap);
 };