<iframe> should expose its mojo::ServiceProvider handle

sky/engine/core/html/HTMLIFrameElement.h

Index: sky/engine/core/html/HTMLIFrameElement.h
diff --git a/sky/engine/core/html/HTMLIFrameElement.h b/sky/engine/core/html/HTMLIFrameElement.h
index a77ba08e119b17abbce39b9ff6eaf8ca4d1ac1cb..56ac0ab6b6decbb9256ea87298f946ba116df7ce 100644
--- a/sky/engine/core/html/HTMLIFrameElement.h
+++ b/sky/engine/core/html/HTMLIFrameElement.h
@@ -26,6 +26,8 @@ public:
 
     mojo::View* contentView() const { return m_contentView; }
 
+    ScriptValue takeServiceProvider(ScriptState*);
+
 private:
     explicit HTMLIFrameElement(Document&);
 
@@ -42,6 +44,7 @@ private:
     void createView();
 
     mojo::View* m_contentView;
+    mojo::ScopedMessagePipeHandle m_serviceProvider;
 };
 
 } // namespace blink