Merge "floss: Scanner: Active scan if no filter, otherwise Passive scan" into main

impl Default for ScanType {

    fn default() -> Self {

        ScanType::Passive

        ScanType::Active

    }

}

        let settings = settings.unwrap_or_else(|| ScanSettings {

            interval: sysprop::get_i32(sysprop::PropertyI32::LeAdvMonScanInterval),

            window: sysprop::get_i32(sysprop::PropertyI32::LeAdvMonScanWindow),

            scan_type: ScanType::default(),

            // TODO(b/290300475): Use the default value (Active) here after the issue is addressed.

            // TODO(b/262746968): Forward the scanning settings from ARC++ APPs.

            // Either of the TODOs above could fix this workaround for the below issues:

            // - b/290300475: Offloaded filtering would be broken on some hardwares if scan mode is

            //                Active. Thus, if |filter| is not none then the scan type should be set

            //                to Passive.

            // - b/328711786: Android only supports Active scan, i.e., ARC++ APPs always expect

            //                Active scan. However, ARC++ bridge is not able to specify the scan

            //                type through the BluetoothLowEnergyScanSession API. Fortunately ARC++

            //                bridge is not able to specify the filter either, so when |filter| is

            //                none we always set the scan type to Active.

            scan_type: if filter.is_none() { ScanType::Active } else { ScanType::Passive },

        });

        // Multiplexing scanners happens at this layer. The implementations of start_scan