Image Capture: remove unnecessary .get() (followup)

Remove unnecessary .get() in unique_ptr<> following up comment [1]

[1] https://codereview.chromium.org/2795693004/#msg18

BUG=700607

Review-Url: https://codereview.chromium.org/2795293002
Cr-Commit-Position: refs/heads/master@{#461794}
1 file changed