GCC: PlaybackImageProvider::Settings: explicitely set copy constructor.

GCC fails to resolve the default copy constructor of the flat_map, so
we add an explicit reference to use default copy constructor.

Bug: 819294

Change-Id: Ie2d69bdbe60742e9253251c965cbf0a936037871
Reviewed-on: https://chromium-review.googlesource.com/944403
Reviewed-by: David Reveman <reveman@chromium.org>
Commit-Queue: José Dapena Paz <jose.dapena@lge.com>
Cr-Commit-Position: refs/heads/master@{#541827}
3 files changed