GitLab

* SendDriveFileTransferEvent and onFileTransfersUpdated are not
  necessay to recieve list because this event is always single.

BUG=408482
TEST=manually
1. Copy the local file to drive.
2. Confirm sync status is updated correctly.

Review URL: https://codereview.chromium.org/542573002

Cr-Commit-Position: refs/heads/master@{#293619}