Support cancellation of non-yet-running jobs in drive::JobScheduler.

chrome/browser/chromeos/drive/job_scheduler.h

Index: chrome/browser/chromeos/drive/job_scheduler.h
diff --git a/chrome/browser/chromeos/drive/job_scheduler.h b/chrome/browser/chromeos/drive/job_scheduler.h
index cc2c3715696c708920655486580dd1c2bb5f81c0..5dc2aa1ca6bfadb9cd09f3eea49cf480193d8ce2 100644
--- a/chrome/browser/chromeos/drive/job_scheduler.h
+++ b/chrome/browser/chromeos/drive/job_scheduler.h
@@ -208,6 +208,10 @@ class JobScheduler
 
     // The callback to cancel the running job. It is returned from task.Run().
     google_apis::CancelCallback cancel_callback;
+
+    // The callback to notify an error to the client of JobScheduler.
+    // This is used to notify cancel of a job that is not running yet.
+    base::Callback<void(google_apis::GDataErrorCode)> abort_callback;
   };
 
   // Parameters for DriveUploader::ResumeUploadFile.