Migrate Chrome OS Bluetooth UI to the new discovery API.

device/bluetooth/bluetooth_discovery_session.cc

Index: device/bluetooth/bluetooth_discovery_session.cc
diff --git a/device/bluetooth/bluetooth_discovery_session.cc b/device/bluetooth/bluetooth_discovery_session.cc
index afeacff7d48a2b640eaf767c925b44e49366b09d..e07df34dd28eb102c4e0c9a8098584e331c11c7e 100644
--- a/device/bluetooth/bluetooth_discovery_session.cc
+++ b/device/bluetooth/bluetooth_discovery_session.cc
@@ -20,6 +20,10 @@ BluetoothDiscoverySession::~BluetoothDiscoverySession() {
   adapter_->DiscoverySessionDestroyed(this);
 }
 
+bool BluetoothDiscoverySession::IsActive() const {
+  return active_;
+}
+
 void BluetoothDiscoverySession::Stop(
     const base::Closure& callback,
     const ErrorCallback& error_callback) {