Revert 219983 "Work-around fix for SyncFS file upload"

> Work-around fix for SyncFS file upload
> 
> Due to the server-side change uploading with etag always seems to fail.
> Don't use etag for uploading to work around until we figure out the
> right fix.
> 
> BUG=278201
> TEST=manual
> R=tzik@chromium.org
> 
> Review URL: https://codereview.chromium.org/23677002

TBR=kinuko@chromium.org

Review URL: https://codereview.chromium.org/23534028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220499 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/sync_file_system/drive_backend/api_util.cc

@@ -909,8 +909,7 @@ void APIUtil::UploadExistingFileInternal(
       entry->resource_id(),
       local_file_path,
       mime_type,
-      // Don't use etag for uploading for now. http://crbug.com/278201
-      std::string(), // entry->etag(),
+      entry->etag(),
       base::Bind(&UploadResultAdapter, did_upload_callback),
       google_apis::ProgressCallback());
 }