Gets HTMLIFrameElement::embedViewManagerClient to work with dart

sky/engine/tonic/mojo_converter.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SKY_ENGINE_TONIC_MOJO_CONVERTER_H_
+#define SKY_ENGINE_TONIC_MOJO_CONVERTER_H_
+
+#include "mojo/public/cpp/system/handle.h"
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+template <typename HandleType>
+struct DartConverter<mojo::ScopedHandleBase<HandleType>> {
+  static mojo::ScopedHandleBase<HandleType> FromDart(Dart_Handle handle) {
+    uint64_t mojo_handle64 = 0;
+    Dart_Handle result = Dart_IntegerToUint64(handle, &mojo_handle64);
+    if (Dart_IsError(result) || !mojo_handle64)
+      return mojo::ScopedHandleBase<HandleType>();
+
+    HandleType mojo_handle(static_cast<MojoHandle>(mojo_handle64));
+    return mojo::MakeScopedHandle(mojo_handle);
+  }
+
+  static Dart_Handle ToDart(mojo::ScopedHandleBase<HandleType> mojo_handle) {
+    return Dart_NewInteger(static_cast<int64_t>(mojo_handle.release().value()));
+  }
+};
+
+}  // namespace blink
+
+#endif  // SKY_ENGINE_TONIC_MOJO_CONVERTER_H_