GitLab

* Previous behavior is to cancel only one item.
* After Issue 400636, this behavior doesn't make sense because only the
  number is decreased.

BUG=414610
TEST=manually
1. Copy the file from Download to Drive.
2. Push the button in syncing status.
3. Confirm all jobs are canceled.

Review URL: https://codereview.chromium.org/576063002

Cr-Commit-Position: refs/heads/master@{#295638}