Add Observatory to sky dart_controller

sky/engine/bindings/builtin_natives.h

Index: sky/engine/bindings/builtin_natives.h
diff --git a/sky/engine/bindings/builtin_natives.h b/sky/engine/bindings/builtin_natives.h
index a08fc193214e1240edbbb4b8759f53acfcdf736d..3f525bc8e64642f0eee547d139c2ba6f7d1d4952 100644
--- a/sky/engine/bindings/builtin_natives.h
+++ b/sky/engine/bindings/builtin_natives.h
@@ -12,12 +12,17 @@ namespace blink {
 
 class BuiltinNatives {
  public:
+  enum IsolateType {
+    MainIsolate,
+    DartIOIsolate,
+  };
+
   static Dart_NativeFunction NativeLookup(Dart_Handle name,
                                           int argument_count,
                                           bool* auto_setup_scope);
   static const uint8_t* NativeSymbol(Dart_NativeFunction native_function);
 
-  static void Init();
+  static void Init(IsolateType isolate_type);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(BuiltinNatives);