PPAPI: Make blocking completion callbacks work.

ppapi/shared_impl/api_callback_type.h

Index: ppapi/shared_impl/api_callback_type.h
diff --git a/ppapi/shared_impl/api_callback_type.h b/ppapi/shared_impl/api_callback_type.h
new file mode 100644
index 0000000000000000000000000000000000000000..7f6f7aed79bbbd5baa6c8821c70e73fe16cc00c5
--- /dev/null
+++ b/ppapi/shared_impl/api_callback_type.h
@@ -0,0 +1,17 @@
+// Copyright (c) 2012 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 PPAPI_SHARED_IMPL_API_CALLBACK_TYPE_H_
+#define PPAPI_SHARED_IMPL_API_CALLBACK_TYPE_H_
+
+#include "base/memory/ref_counted.h"
+#include "ppapi/shared_impl/tracked_callback.h"
+
+namespace ppapi {
+
+typedef scoped_refptr<TrackedCallback> ApiCallbackType;
+
+}  // namespace ppapi
+
+#endif  // PPAPI_SHARED_IMPL_API_CALLBACK_TYPE_H_