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

chrome/browser/chromeos/gdata/gdata_file_system.h

Index: chrome/browser/chromeos/gdata/gdata_file_system.h
diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.h b/chrome/browser/chromeos/gdata/gdata_file_system.h
index 0ae0f20b5ff82a5ed49060b00b107ccd098dd771..8de1981b95b1f30ea224157c7fb25f5a247f3f2d 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -74,6 +74,9 @@ class GDataFileSystem : public GDataFileSystemInterface,
                         const OpenFileCallback& callback) OVERRIDE;
   virtual void CloseFile(const FilePath& file_path,
                          const FileOperationCallback& callback) OVERRIDE;
+  virtual void PrepareWritableFileAndRun(
+      const FilePath& file_path,
+      const OpenFileCallback& callback) OVERRIDE;
   virtual void Copy(const FilePath& src_file_path,
                     const FilePath& dest_file_path,
                     const FileOperationCallback& callback) OVERRIDE;
@@ -855,6 +858,24 @@ class GDataFileSystem : public GDataFileSystemInterface,
     GDataFileError error,
     scoped_ptr<GDataEntryProto> entry_proto);
 
+  // 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);
+
   // All members should be accessed only on UI thread. Do not post tasks to
   // other threads with base::Unretained(this).
   scoped_ptr<GDataDirectoryService> directory_service_;