gdata: Fix "save as pdf" to work on Google Drive.

chrome/browser/chromeos/gdata/gdata_file_write_helper.h

+// Copyright (c) 2012 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 CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_WRITE_HELPER_H_
+#define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_WRITE_HELPER_H_
+
+#include "base/bind.h"
+#include "base/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/chromeos/gdata/gdata_errorcode.h"
+#include "chrome/browser/chromeos/gdata/gdata_file_system_interface.h"
+
+namespace gdata {
+
+// This class provides higher level operations for writing to GData files over
+// GDataFileSystemInterface.
+class GDataFileWriteHelper {

[satorux1, 2012/08/02 06:56:53]

We can remove "GData" prefix from the class, and the file name. Historically,
we've been abusing the term "gdata" to mean both GDATA API and Drive, but we
should stop doing that.

[kinaba, 2012/08/02 07:22:39]

Done.

+ public:
+  explicit GDataFileWriteHelper(GDataFileSystemInterface* file_system);
+  ~GDataFileWriteHelper();
+
+  // Prepares a local temporary file path and passes it to |callback| on the
+  // blocking thread pool that allows file operations. The modification to
+  // the file is reflected to GData |path|. If |path| does not exist, a new
+  // file is created.
+  //
+  // Can be called from UI/IO thread.
+  void PrepareWritableFileAndRun(const FilePath& path,
+                                 const OpenFileCallback& callback);
+
+ private:
+  // Part of PrepareWritableFilePathAndRun(). It forwards the task to the UI
+  // thread, tries CreateFile for the case file does not exist yet, does
+  // OpenFile to download and mark the file as dirty, runs |callback|, and
+  // finally calls CloseFile.
+  void PrepareWritableFileAndRunOnUIThread(
+      const FilePath& file_path,
+      const OpenFileCallback& callback);
+  void PrepareWritableFileAndRunAfterCreateFile(
+      const FilePath& file_path,
+      const OpenFileCallback& callback,
+      GDataFileError result);
+  void PrepareWritableFileAndRunAfterOpenFile(
+      const FilePath& file_path,
+      const OpenFileCallback& callback,
+      GDataFileError result,
+      const FilePath& local_cache_path);
+  void PrepareWritableFileAndRunAfterCallback(const FilePath& file_path);
+
+  // File system owned by GDataSystemService.
+  GDataFileSystemInterface* file_system_;
+
+  // WeakPtrFactory and WeakPtr bound to the UI thread.
+  base::WeakPtrFactory<GDataFileWriteHelper> weak_ptr_factory_;
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_WRITE_HELPER_H_