Change ArrayBuffer API and implementation to use embedder-provided allocator.

src/v8.h

Index: src/v8.h
diff --git a/src/v8.h b/src/v8.h
index cd25dc76ea46edf52d372852cc530a6c750f8ccc..ac05dfd4e72f98e0d5910881302470fe600277f6 100644
--- a/src/v8.h
+++ b/src/v8.h
@@ -121,6 +121,15 @@ class V8 : public AllStatic {
   static void RemoveCallCompletedCallback(CallCompletedCallback callback);
   static void FireCallCompletedCallback(Isolate* isolate);
 
+  static v8::ArrayBuffer::Allocator* ArrayBufferAllocator() {
+    return array_buffer_allocator_;
+  }
+
+  static void SetArrayBufferAllocator(v8::ArrayBuffer::Allocator *allocator) {
+    CHECK_EQ(NULL, array_buffer_allocator_);
+    array_buffer_allocator_ = allocator;
+  }
+
  private:
   static void InitializeOncePerProcessImpl();
   static void InitializeOncePerProcess();
@@ -139,6 +148,8 @@ class V8 : public AllStatic {
   static bool use_crankshaft_;
   // List of callbacks when a Call completes.
   static List<CallCompletedCallback>* call_completed_callbacks_;
+  // Allocator for external array buffers.
+  static v8::ArrayBuffer::Allocator* array_buffer_allocator_;
 };