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diff --git a/WebKit/chromium/src/WorkerFileWriterCallbacksBridge.h b/WebKit/chromium/src/WorkerFileWriterCallbacksBridge.h
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+/*
+ * Copyright (C) 2010 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WorkerFileWriterCallbacksBridge_h
+#define WorkerFileWriterCallbacksBridge_h
+
+#if ENABLE(FILE_SYSTEM)
+
+#include "WebFileError.h"
+#include "WebFileWriterClient.h"
+#include "WorkerContext.h"
+#include <wtf/PassOwnPtr.h>
+#include <wtf/PassRefPtr.h>
+#include <wtf/ThreadSafeShared.h>
+
+namespace WebCore {
+    class AsyncFileWriterClient;
+    class KURL;
+    class WorkerLoaderProxy;
+}
+
+namespace WTF {
+    class String;
+}
+using WTF::String;
+
+namespace WebKit {
+
+class WebFileSystem;
+class WebFileWriter;
+class WebFileWriterClient;
+class WebWorkerBase;
+
+// This class is used as a mechanism to bridge calls between threads.
+// Calls to a WebFileWriter must happen on the main thread, but they come from
+// the context thread. The responses through the WebFileWriterClient interface
+// start on the main thread, but must be sent via the worker context thread.
+//
+// A typical flow for write would look like this:
+// Bridge::postWriteToMainThread() on WorkerThread
+//  --> Bridge::writeOnMainThread() is called on MainThread
+//  --> WebFileWriter::write()
+//      This makes an IPC; the actual operation is down in the browser.
+//  --> Bridge::didWrite is called on MainThread
+//  --> Bridge::didWriteOnWorkerThread is called on WorkerThread
+//      This calls the original client (m_clientOnWorkerThread).
+//
+// The bridge object is refcounted, so that it doesn't get deleted while there
+// are cross-thread calls in flight. Each CrossThreadTask carries a reference
+// to the bridge, which guarantees that the bridge will still be valid when the
+// task is executed. In order to shut down the bridge, the WebFileWriterClient
+// should call postShutdownToMainThread before dropping its reference to the
+// bridge. This ensures that the WebFileWriter will be cleared on the main
+// thread and that no further calls to the WebFileWriterClient will be made.
+class WorkerFileWriterCallbacksBridge : public ThreadSafeShared<WorkerFileWriterCallbacksBridge>, public WebCore::WorkerContext::Observer, public WebFileWriterClient {
+public:
+    ~WorkerFileWriterCallbacksBridge();
+
+    // WorkerContext::Observer method.
+    virtual void notifyStop();
+
+    static PassRefPtr<WorkerFileWriterCallbacksBridge> create(const String& path, WebCore::WorkerLoaderProxy* proxy, WebCore::ScriptExecutionContext* workerContext, WebCore::AsyncFileWriterClient* client)
+    {
+        return adoptRef(new WorkerFileWriterCallbacksBridge(path, proxy, workerContext, client));
+    }
+
+    // Methods that create an instance and post an initial request task to the main thread. They must be called on the worker thread.
+    void postWriteToMainThread(long long position, const WebCore::KURL& data);
+    void postTruncateToMainThread(long long length);
+    void postAbortToMainThread();
+
+    // The owning WorkerAsyncFileWriterChromium should call this method before dropping its last reference to the bridge, on the context thread.
+    // The actual deletion of the WorkerFileWriterCallbacksBridge may happen on either the main or context thread, depending on where the last reference goes away; that's safe as long as this is called first.
+    void postShutdownToMainThread(PassRefPtr<WorkerFileWriterCallbacksBridge>);
+
+    // Callback methods that are called on the main thread.
+    // These are the implementation of WebKit::WebFileWriterClient.
+    void didWrite(long long bytes, bool complete);
+    void didFail(WebFileError);
+    void didTruncate();
+
+private:
+    WorkerFileWriterCallbacksBridge(const String& path, WebCore::WorkerLoaderProxy*, WebCore::ScriptExecutionContext*, WebCore::AsyncFileWriterClient*);
+
+    void postInitToMainThread(const String& path);
+
+    // Methods that are to be called on the main thread.
+    static void writeOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, long long position, const WebCore::KURL& data);
+    static void truncateOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, long long length);
+    static void abortOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>);
+    static void initOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, const String& path);
+    static void shutdownOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>);
+
+    // Methods that dispatch to AsyncFileWriterClient on the worker threads.
+    static void didWriteOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, long long length, bool complete);
+    static void didFailOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, WebFileError);
+    static void didTruncateOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>);
+
+    // Called on the main thread to run the supplied task.
+    static void runTaskOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
+    // Called on the worker thread to run the supplied task.
+    static void runTaskOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
+
+    // Called on the worker thread to dispatch to the main thread.
+    void dispatchTaskToMainThread(PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
+    // Called on the main thread to dispatch to the worker thread.
+    void dispatchTaskToWorkerThread(PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
+
+    // Used from the main thread to post tasks to the context thread.
+    WebCore::WorkerLoaderProxy* m_proxy;
+
+    // Used on the context thread, only to check that we're running on the context thread.
+    WebCore::ScriptExecutionContext* m_workerContext;
+
+    // Created and destroyed from the main thread.
+    OwnPtr<WebKit::WebFileWriter> m_writer;
+
+    // Used on the context thread to call back into the client.
+    WebCore::AsyncFileWriterClient* m_clientOnWorkerThread;
+
+    // Used to indicate that shutdown has started on the main thread, and hence the writer has been deleted.
+    bool m_writerDeleted;
+};
+
+} // namespace WebCore
+
+#endif
+
+#endif // WorkerFileWriterCallbacksBridge_h