Add external byte array API and finalize external strings and byte arrays.

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index 4bb9504e544c2f2bcfad0fd9a987cf1dffa9dc8e..93d269bd141c09710fa59f6b6966a5ece6c3bc21 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -895,13 +895,25 @@ class RawFourByteString : public RawString {
 template<typename T>
 class ExternalStringData {
  public:
-  typedef void Callback(void* peer);
-  ExternalStringData(const T* data, void* peer, Callback* callback) :
+  ExternalStringData(const T* data, void* peer, Dart_PeerFinalizer callback) :
       data_(data), peer_(peer), callback_(callback) {
   }
+
+  ~ExternalStringData() {
+    if (callback_ != NULL) (*callback_)(peer_);
+  }
+
+  const T* data() {
+    return data_;
+  }
+  void* peer() {
+    return peer_;
+  }
+
+ private:
   const T* data_;
   void* peer_;
-  Callback* callback_;
+  Dart_PeerFinalizer callback_;
 };
 
 
@@ -983,10 +995,36 @@ class RawInternalByteArray : public RawByteArray {
 };
 
 
+class ExternalByteArrayData {
+ public:
+  ExternalByteArrayData(uint8_t* data,
+                        void* peer,
+                        Dart_PeerFinalizer callback) :
+      data_(data), peer_(peer), callback_(callback) {
+  }
+
+  ~ExternalByteArrayData() {
+    if (callback_ != NULL) (*callback_)(peer_);
+  }
+
+  uint8_t* data() {
+    return data_;
+  }
+  void* peer() {
+    return peer_;
+  }
+
+ private:
+  uint8_t* data_;
+  void* peer_;
+  Dart_PeerFinalizer callback_;
+};
+
+
 class RawExternalByteArray : public RawByteArray {
   RAW_HEAP_OBJECT_IMPLEMENTATION(ExternalByteArray);
 
-  uint8_t* data_;
+  ExternalByteArrayData* external_data_;
 };