GitLab

The CL lets DriveUploader use batch request API. DriveUploader does asynchronous
preparation before calling API on service interface. To hold batch request
during the asynchronous preparation, the CL introduce refcounted hepler class,
which manages life time of batch request configurator.

BUG=451917
TEST=DriveUploaderTest

Review URL: https://codereview.chromium.org/1134633003

Cr-Commit-Position: refs/heads/master@{#329599}