Verify a bit more about external strings

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 508 matching lines @@
 
 void Heap::RepairFreeListsAfterDeserialization() {
   PagedSpaces spaces(this);
   for (PagedSpace* space = spaces.next(); space != NULL;
        space = spaces.next()) {
     space->RepairFreeListsAfterDeserialization();
   }
 }
 
 
+void Heap::FinalizeExternalString(String* string) {
+  DCHECK(string->IsExternalString());
+  v8::String::ExternalStringResourceBase** resource_addr =
+      reinterpret_cast<v8::String::ExternalStringResourceBase**>(
+          reinterpret_cast<byte*>(string) + ExternalString::kResourceOffset -
+          kHeapObjectTag);
+
+  // Dispose of the C++ object if it has not already been disposed.
+  if (*resource_addr != NULL) {
+#ifdef V8_ENABLE_CHECKS
+    {
+      HandleScope scope(string->GetIsolate());
+      i::Handle<i::String> str_obj(string);
+      v8::Utils::ToLocal(str_obj)->VerifyExternalStringResourceBase(
+          *resource_addr, StringShape(string).IsExternalOneByte()
+                              ? v8::String::ONE_BYTE_ENCODING
+                              : v8::String::TWO_BYTE_ENCODING);
+    }
+#endif
+    (*resource_addr)->Dispose();
+    *resource_addr = NULL;
+  }
+}
+
+
 void Heap::ProcessPretenuringFeedback() {
   if (FLAG_allocation_site_pretenuring) {
     int tenure_decisions = 0;
     int dont_tenure_decisions = 0;
     int allocation_mementos_found = 0;
     int allocation_sites = 0;
     int active_allocation_sites = 0;
 
     // If the scratchpad overflowed, we have to iterate over the allocation
     // sites list.
@@ skipping 6014 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }  // namespace internal
 }  // namespace v8