arc/bluetooth: plumb adapter discoverable timeout property

components/arc/bluetooth/arc_bluetooth_bridge.cc

Index: components/arc/bluetooth/arc_bluetooth_bridge.cc
diff --git a/components/arc/bluetooth/arc_bluetooth_bridge.cc b/components/arc/bluetooth/arc_bluetooth_bridge.cc
index b17ea3c835159d42064efa96b22dca7b72202501..bc9703dc72aabd33b34da26114a02904d0344ac6 100644
--- a/components/arc/bluetooth/arc_bluetooth_bridge.cc
+++ b/components/arc/bluetooth/arc_bluetooth_bridge.cc
@@ -27,6 +27,7 @@
 #include "device/bluetooth/bluetooth_remote_gatt_characteristic.h"
 #include "device/bluetooth/bluetooth_remote_gatt_descriptor.h"
 #include "device/bluetooth/bluetooth_remote_gatt_service.h"
+#include "device/bluetooth/bluez/bluetooth_adapter_bluez.h"
 
 using device::BluetoothAdapter;
 using device::BluetoothAdapterFactory;
@@ -1185,7 +1186,8 @@ ArcBluetoothBridge::GetAdapterProperties(
   if (type == mojom::BluetoothPropertyType::ALL ||
       type == mojom::BluetoothPropertyType::ADAPTER_DISCOVERY_TIMEOUT) {
     mojom::BluetoothPropertyPtr btp = mojom::BluetoothProperty::New();
-    btp->set_discovery_timeout(120);
+    btp->set_discovery_timeout(static_cast<bluez::BluetoothAdapterBlueZ*>(

[Ken Rockot(use gerrit already), 2016/06/27 17:10:49]

drive-by comment: could you just store bluetooth_adapter_ as a
bluez::BluetoothAdapterBlueZ and do the downcast once in OnAdapterInitialized,
with a comment explaining why the downcast is safe?

+        bluetooth_adapter_.get())->GetDiscoverableTimeout());
     properties.push_back(std::move(btp));
   }