Implement ReferenceType.Instances.

Change-Id: I6a72fc4c748e7041fedcb615eca2b86b1f28bb63
diff --git a/src/heap.h b/src/heap.h
index bd9945d..fd08f29 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -173,6 +173,10 @@
                       uint64_t* counts)
       LOCKS_EXCLUDED(Locks::heap_bitmap_lock_)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  // Implements JDWP RT_Instances.
+  void GetInstances(Class* c, int32_t max_count, std::vector<Object*>& instances)
+      LOCKS_EXCLUDED(Locks::heap_bitmap_lock_)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Removes the growth limit on the alloc space so it may grow to its maximum capacity. Used to
   // implement dalvik.system.VMRuntime.clearGrowthLimit.