Add request header on gdata operation for testing ETag match.

chrome/browser/google_apis/gdata_wapi_service.h

Index: chrome/browser/google_apis/gdata_wapi_service.h
diff --git a/chrome/browser/google_apis/gdata_wapi_service.h b/chrome/browser/google_apis/gdata_wapi_service.h
index d6822a17871791f611a0459b6d386e0dc31c9927..3dcae707a9b31c08d8de1dd4d7ba3fdc15f51219 100644
--- a/chrome/browser/google_apis/gdata_wapi_service.h
+++ b/chrome/browser/google_apis/gdata_wapi_service.h
@@ -68,17 +68,20 @@ class GDataWapiService : public DriveServiceInterface,
       const gdata::GetDataCallback& callback) OVERRIDE;
   virtual void DeleteDocument(
       const GURL& document_url,
+      const std::string& etag,
       const gdata::EntryActionCallback& callback) OVERRIDE;
   virtual void DownloadDocument(
       const FilePath& virtual_path,
       const FilePath& local_cache_path,
       const GURL& content_url,
       DocumentExportFormat format,
+      const std::string& etag,
       const gdata::DownloadActionCallback& callback) OVERRIDE;
   virtual void DownloadFile(
       const FilePath& virtual_path,
       const FilePath& local_cache_path,
       const GURL& content_url,
+      const std::string& etag,
       const gdata::DownloadActionCallback& download_action_callback,
       const gdata::GetContentCallback& get_content_callback) OVERRIDE;
   virtual void CopyDocument(const std::string& resource_id,