[Fetch API] Introduce BytesConsumer

third_party/WebKit/Source/modules/fetch/BytesConsumerForDataConsumerHandle.h

+// Copyright 2016 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 BytesConsumerForDataConsumerHandle_h
+#define BytesConsumerForDataConsumerHandle_h
+
+#include "modules/ModulesExport.h"
+#include "modules/fetch/BytesConsumer.h"
+#include "modules/fetch/FetchFormDataConsumerHandle.h"
+#include "platform/heap/Handle.h"
+#include "public/platform/WebDataConsumerHandle.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/text/WTFString.h"
+
+#include <memory>
+
+namespace blink {
+
+class MODULES_EXPORT BytesConsumerForDataConsumerHandle final : public BytesConsumer, public WebDataConsumerHandle::Client {
+    EAGERLY_FINALIZE();
+    DECLARE_EAGER_FINALIZATION_OPERATOR_NEW();
+public:
+    explicit BytesConsumerForDataConsumerHandle(std::unique_ptr<FetchDataConsumerHandle>);
+    ~BytesConsumerForDataConsumerHandle() override;
+
+    Result read(char* buffer, size_t /* size */, size_t* readSize) override;
+    Result beginRead(const char** buffer, size_t* available) override;
+    PassRefPtr<BlobDataHandle> drainAsBlobDataHandle(BlobSizePolicy) override;
+    PassRefPtr<EncodedFormData> drainAsFormData() override;
+    Result endRead(size_t readSize) override;
+    void setClient(BytesConsumer::Client*) override;
+    void clearClient() override;
+
+    void cancel() override;
+    PublicState getPublicState() const override;
+    Error getError() const override
+    {
+        DCHECK(m_state == InternalState::Errored);
+        return m_error;
+    }
+    String debugName() const override { return "BytesConsumerForDataConsumerHandle"; }
+
+    // WebDataConsumerHandle::Client
+    void didGetReadable() override;
+
+    DECLARE_TRACE();
+
+private:
+    void close();
+    void error();
+
+    std::unique_ptr<FetchDataConsumerHandle::Reader> m_reader;
+    Member<BytesConsumer::Client> m_client;
+    InternalState m_state = InternalState::Waiting;
+    Error m_error;
+};
+
+} // namespace blink
+
+#endif // BytesConsumerForDataConsumerHandle_h