Add request header on gdata operation for testing ETag match.

chrome/browser/chromeos/drive/drive_uploader.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_DRIVE_DRIVE_UPLOADER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_UPLOADER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 141 matching lines @@
 
     gdata::UploadMode upload_mode;
 
     // Location URL used to get |upload_location| with InitiateUpload.
     GURL initial_upload_location;
 
     // Location URL where file is to be uploaded to, returned from
     // InitiateUpload. Used for the subsequent ResumeUpload requests.
     GURL upload_location;
 
+    // ETag to match to the destination file. Leave this empty if not needed.

[kochi, 2012/10/16 05:04:58]

nit: "match the destination file"

[tzik, 2012/10/16 05:48:05]

Done.

+    std::string etag;
+
     // Final path in gdata. Looks like /special/drive/MyFolder/MyFile.
     FilePath drive_path;
 
     // TODO(achuith): Use generic stream object after FileStream is refactored
     // to extend a generic stream.
     //
     // For opening and reading from physical file.
     scoped_ptr<net::FileStream> file_stream;
     scoped_refptr<net::IOBuffer> buf;  // Holds current content to be uploaded.
     // Size of |buf|, max is 512KB; Google Docs requires size of each upload
@@ skipping 96 matching lines @@
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<DriveUploader> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DriveUploader);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_UPLOADER_H_