Add methods to enable configuration of ResourceConstraints based on limits derived at runtime.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index fd361fc7a4655709385ab0f560b750caf8990c8a..c98237a1f59c4bdb575478542be1d52cde5529e1 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -2337,6 +2337,10 @@ class Heap {
   // configured through the API until it is set up.
   bool configured_;
 
+  // Flag is set if the heap has been configured with any value different from
+  // the default values.
+  bool limits_changed_from_defaults_;

[Hannes Payer (out of office), 2013/09/19 14:50:57]

Why do we need that? If the embedder decides to overwrite multiple times that
should be ok? Or is there a problem?

[rmcilroy, 2013/09/19 15:01:34]

This is not to prevent the embedder overwriting things multiple times (that's
fine, and still works after this CL), it is to prevent the is_memory_constrained
flag resetting the default values if the embedder has already changed the values
from their defaults (i.e., if the embedder specifically sets limits, treat the
preferentially to any changes which would be incurred by setting the
is_memory_constrained flag).

+
   ExternalStringTable external_string_table_;
 
   VisitorDispatchTable<ScavengingCallback> scavenging_visitors_table_;