- Add the ability to protect VirtualMemory.

runtime/vm/heap.cc

Index: runtime/vm/heap.cc
===================================================================
--- runtime/vm/heap.cc	(revision 9969)
+++ runtime/vm/heap.cc	(working copy)
@@ -36,7 +36,7 @@
             "code heap size in MB,"
             "e.g: --code_heap_size=8 allocates a 8MB code heap");
 
-Heap::Heap() {
+  Heap::Heap() : read_only_(false) {
   new_space_ = new Scavenger(this,
                              (FLAG_new_gen_heap_size * MB),
                              kNewObjectAlignmentOffset);
@@ -226,6 +226,15 @@
 }
 
 
+void Heap::WriteProtect(bool read_only) {
+  read_only_ = read_only;
+  new_space_->WriteProtect(read_only);
+  old_space_->WriteProtect(read_only);
+  // TODO(iposva): Merge old and code space.
+  // code_space_->WriteProtect(read_only);
+}
+
+
 uword Heap::TopAddress() {
   return reinterpret_cast<uword>(new_space_->TopAddress());
 }