Handle RESCAN events from the Bluetooth chooser by starting or extending a discovery session.

device/bluetooth/test/mock_bluetooth_adapter.cc

Index: device/bluetooth/test/mock_bluetooth_adapter.cc
diff --git a/device/bluetooth/test/mock_bluetooth_adapter.cc b/device/bluetooth/test/mock_bluetooth_adapter.cc
index 8054d6905ba7724383590a4d5545d257e1ad8141..26ae68b83ce4e98ca6dae21c2516c0d1f311e986 100644
--- a/device/bluetooth/test/mock_bluetooth_adapter.cc
+++ b/device/bluetooth/test/mock_bluetooth_adapter.cc
@@ -8,10 +8,21 @@
 
 namespace device {
 
+using testing::Invoke;
+using testing::_;
+
 MockBluetoothAdapter::Observer::Observer() {}
 MockBluetoothAdapter::Observer::~Observer() {}
 
 MockBluetoothAdapter::MockBluetoothAdapter() {
+  ON_CALL(*this, AddObserver(_))
+      .WillByDefault(Invoke([this](BluetoothAdapter::Observer* observer) {
+        this->BluetoothAdapter::AddObserver(observer);
+      }));
+  ON_CALL(*this, RemoveObserver(_))
+      .WillByDefault(Invoke([this](BluetoothAdapter::Observer* observer) {
+        this->BluetoothAdapter::RemoveObserver(observer);
+      }));
 }
 
 MockBluetoothAdapter::~MockBluetoothAdapter() {}