Add FetchDataConsumerHandle and utility functions/classes

Source/modules/fetch/DataConsumerHandleUtil.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 DataConsumerHandleUtil_h
+#define DataConsumerHandleUtil_h
+
+#include "modules/fetch/FetchDataConsumerHandle.h"
+#include "public/platform/WebDataConsumerHandle.h"
+#include "wtf/PassOwnPtr.h"
+#include "wtf/WeakPtr.h"
+
+namespace blink {
+
+// Returns a handle that returns ShouldWait for read / beginRead and
+// UnexpectedError for endRead.
+PassOwnPtr<WebDataConsumerHandle> createWaitingHandle();

[yhirano, 2015/06/17 04:13:34]

I'm afraid blink::createWaitingHandle and others are too generic. Can you put
them in a class, or name them longer?

[hiroshige, 2015/06/17 08:30:23]

Made names longer.

+
+// Returns a handle that returns Done for read / beginRead and
+// UnexpectedError for endRead.
+PassOwnPtr<WebDataConsumerHandle> createDoneHandle();
+
+// Returns a handle that returns UnexpectedError for read / beginRead /
+// endRead.
+PassOwnPtr<WebDataConsumerHandle> createUnexpectedErrorHandle();
+
+// Returns a FetchDataConsumerHandle that wraps WebDataConsumerHandle.
+PassOwnPtr<FetchDataConsumerHandle> createFetchHandleFromWebHandle(PassOwnPtr<WebDataConsumerHandle>);
+
+// A helper class to call Client::didGetReadable() asynchronously after
+// Reader creation.
+class NotifyOnReaderCreationHelper {

[yhirano, 2015/06/17 04:13:34]

Do you want to expose this class? Is it a problem to move it into the
implementation?

[yhirano, 2015/06/17 04:13:34]

+final

[hiroshige, 2015/06/17 08:30:23]

Done.

[hiroshige, 2015/06/17 08:30:23]

I'd like to use this in FetchBlobConsumerHandle and thus expose this.

+public:
+    NotifyOnReaderCreationHelper(WebDataConsumerHandle::Client*);
+
+private:
+    void notify(WebDataConsumerHandle::Client*);
+
+    WeakPtrFactory<NotifyOnReaderCreationHelper> m_factory;
+};
+
+} // namespace blink
+
+#endif // DataConsumerHandleUtil_h