Add comments into weave::provider::ConfigStore Removes OnSettingsChanged which had to be removed by CL:1200 BUG:24267885 Change-Id: I790d7e158927a0e2fbcd34e820075a213a759187 Reviewed-on: https://weave-review.googlesource.com/1204 Reviewed-by: Vitaly Buka <vitalybuka@google.com>