Add FetchDataConsumerHandle and utility functions/classes

Source/modules/fetch/DataConsumerHandleUtil.cpp

Index: Source/modules/fetch/DataConsumerHandleUtil.cpp
diff --git a/Source/modules/fetch/DataConsumerHandleUtil.cpp b/Source/modules/fetch/DataConsumerHandleUtil.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..587b92628168468b8e970e4809d1ed2ade7d8d63
--- /dev/null
+++ b/Source/modules/fetch/DataConsumerHandleUtil.cpp
@@ -0,0 +1,151 @@
+// 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.
+
+#include "config.h"
+#include "modules/fetch/DataConsumerHandleUtil.h"
+
+#include "platform/Task.h"
+#include "platform/blob/BlobData.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebThread.h"
+#include "public/platform/WebTraceLocation.h"
+#include "wtf/Functional.h"
+
+namespace blink {
+
+using Result = WebDataConsumerHandle::Result;
+
+namespace {
+
+class WaitingHandle final : public WebDataConsumerHandle {
+private:
+    class ReaderImpl final : public WebDataConsumerHandle::Reader {
+    public:
+        Result read(void*, size_t, WebDataConsumerHandle::Flags, size_t *readSize) override
+        {
+            *readSize = 0;
+            return ShouldWait;
+        }
+        Result beginRead(const void** buffer, WebDataConsumerHandle::Flags, size_t *available) override
+        {
+            *available = 0;
+            *buffer = nullptr;
+            return ShouldWait;
+        }
+        Result endRead(size_t) override
+        {
+            return UnexpectedError;
+        }
+    };
+    Reader* obtainReaderInternal(Client*) override { return new ReaderImpl; }
+};
+
+class RepeatingReader final : public WebDataConsumerHandle::Reader {
+public:
+    explicit RepeatingReader(Result result, WebDataConsumerHandle::Client* client) : m_result(result), m_notifier(client) { }
+
+private:
+    Result read(void*, size_t, WebDataConsumerHandle::Flags, size_t *readSize) override
+    {
+        *readSize = 0;
+        return m_result;
+    }
+    Result beginRead(const void** buffer, WebDataConsumerHandle::Flags, size_t *available) override
+    {
+        *available = 0;
+        *buffer = nullptr;
+        return m_result;
+    }
+    Result endRead(size_t) override
+    {
+        return WebDataConsumerHandle::UnexpectedError;
+    }
+
+    Result m_result;
+    NotifyOnReaderCreationHelper m_notifier;
+};
+
+class DoneHandle final : public WebDataConsumerHandle {
+private:
+    Reader* obtainReaderInternal(Client* client) override { return new RepeatingReader(Done, client); }
+};
+
+class UnexpectedErrorHandle final : public WebDataConsumerHandle {
+private:
+    Reader* obtainReaderInternal(Client* client) override { return new RepeatingReader(UnexpectedError, client); }
+};
+
+class WebToFetchDataConsumerHandleAdapter : public FetchDataConsumerHandle {
+public:
+    WebToFetchDataConsumerHandleAdapter(PassOwnPtr<WebDataConsumerHandle> handle) : m_handle(handle) { }
+private:
+    class ReaderImpl final : public FetchDataConsumerHandle::Reader {
+    public:
+        ReaderImpl(PassOwnPtr<WebDataConsumerHandle::Reader> reader) : m_reader(reader) { }
+        Result read(void* data, size_t size, Flags flags, size_t* readSize) override
+        {
+            return m_reader->read(data, size, flags, readSize);
+        }
+
+        Result beginRead(const void** buffer, Flags flags, size_t* available) override
+        {
+            return m_reader->beginRead(buffer, flags, available);
+        }
+        Result endRead(size_t readSize) override
+        {
+            return m_reader->endRead(readSize);
+        }
+    private:
+        OwnPtr<WebDataConsumerHandle::Reader> m_reader;
+    };
+
+    Reader* obtainReaderInternal(Client* client) override { return new ReaderImpl(m_handle->obtainReader(client)); }
+
+    OwnPtr<WebDataConsumerHandle> m_handle;
+};
+
+} // namespace
+
+PassOwnPtr<WebDataConsumerHandle> createWaitingDataConsumerHandle()
+{
+    return adoptPtr(new WaitingHandle);
+}
+
+PassOwnPtr<WebDataConsumerHandle> createDoneDataConsumerHandle()
+{
+    return adoptPtr(new DoneHandle);
+}
+
+PassOwnPtr<WebDataConsumerHandle> createUnexpectedErrorDataConsumerHandle()
+{
+    return adoptPtr(new UnexpectedErrorHandle);
+}
+
+PassOwnPtr<FetchDataConsumerHandle> createFetchDataConsumerHandleFromWebHandle(PassOwnPtr<WebDataConsumerHandle> handle)
+{
+    return adoptPtr(new WebToFetchDataConsumerHandleAdapter(handle));
+}
+
+NotifyOnReaderCreationHelper::NotifyOnReaderCreationHelper(WebDataConsumerHandle::Client* client)
+    : m_factory(this)
+{
+    if (!client)
+        return;
+    // Note we don't need thread safety here because this object is
+    // bound to the current thread.
+    Platform::current()->currentThread()->postTask(FROM_HERE, new Task(bind(&NotifyOnReaderCreationHelper::notify, m_factory.createWeakPtr(), client)));
+}
+
+void NotifyOnReaderCreationHelper::notify(WebDataConsumerHandle::Client* client)
+{
+    // |client| dereference is safe here because:
+    // - |this| is owned by a reader,
+    //   so the reader outlives |this|, and
+    // - |client| is the client of the reader, so |client| outlives the reader
+    //   (guaranteed by the user of the reader),
+    // and therefore |client| outlives |this|.
+    client->didGetReadable();
+}
+
+} // namespace blink