Introduce DataConsumerHandleTee

Source/modules/fetch/DataConsumerTee.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 DataConsumerTee_h
+#define DataConsumerTee_h
+
+#include "public/platform/WebDataConsumerHandle.h"
+
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
+
+namespace blink {
+
+class ExecutionContext;
+
+class DataConsumerTee {
+public:
+    // Create two handles from one. |src| must be a valid unlocked handle.
+    static void create(ExecutionContext*, PassOwnPtr<WebDataConsumerHandle> src, OwnPtr<WebDataConsumerHandle>* dest1, OwnPtr<WebDataConsumerHandle>* dest2);
+};
+
+} // namespace blink
+
+#endif // DataConsumerTee_h