WIP: Implement 5xx Error handling.

chrome/browser/google_apis/drive_service_interface.h

Index: chrome/browser/google_apis/drive_service_interface.h
diff --git a/chrome/browser/google_apis/drive_service_interface.h b/chrome/browser/google_apis/drive_service_interface.h
index 8dfb3ba83e2ce9ef2e2f13d6bb7bc5254228e606..20498db7a3eddc4bf2053318d3d9580a9a342152 100644
--- a/chrome/browser/google_apis/drive_service_interface.h
+++ b/chrome/browser/google_apis/drive_service_interface.h
@@ -242,6 +242,15 @@ class DriveServiceInterface {
   virtual void ResumeUpload(const ResumeUploadParams& params,
                             const ResumeUploadCallback& callback) = 0;
 
+  // Returns the current uploading state from the server.
+  // |callback| must not be null.
+  virtual void GetUploadState(
+      const UploadMode upload_mode,
+      const FilePath& drive_file_path,
+      const GURL& upload_url,
+      int64 content_length,
+      const ResumeUploadCallback& callback) = 0;
+
   // Authorizes a Drive app with the id |app_id| to open the given file.
   // Upon completion, invokes |callback| with the link to open the file with
   // the provided app. |callback| must not be null.