Provide a convenience array buffer allocator

samples/hello-world.cc

Index: samples/hello-world.cc
diff --git a/samples/hello-world.cc b/samples/hello-world.cc
index 902d8d55461c673090c8661c125fcee34a2ba1e3..9e5188f4792ca8e16875f70b334d5f1addbaa1c5 100644
--- a/samples/hello-world.cc
+++ b/samples/hello-world.cc
@@ -11,17 +11,6 @@
 
 using namespace v8;
 
-class ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
- public:
-  virtual void* Allocate(size_t length) {
-    void* data = AllocateUninitialized(length);
-    return data == NULL ? data : memset(data, 0, length);
-  }
-  virtual void* AllocateUninitialized(size_t length) { return malloc(length); }
-  virtual void Free(void* data, size_t) { free(data); }
-};
-
-
 int main(int argc, char* argv[]) {
   // Initialize V8.
   V8::InitializeICUDefaultLocation(argv[0]);
@@ -31,9 +20,9 @@ int main(int argc, char* argv[]) {
   V8::Initialize();
 
   // Create a new Isolate and make it the current one.
-  ArrayBufferAllocator allocator;
   Isolate::CreateParams create_params;
-  create_params.array_buffer_allocator = &allocator;
+  create_params.array_buffer_allocator =
+      v8::ArrayBuffer::Allocator::NewDefaultAllocator();
   Isolate* isolate = Isolate::New(create_params);
   {
     Isolate::Scope isolate_scope(isolate);
@@ -68,5 +57,6 @@ int main(int argc, char* argv[]) {
   V8::Dispose();
   V8::ShutdownPlatform();
   delete platform;
+  delete create_params.array_buffer_allocator;
   return 0;
 }