Bluetooth: mac: add connected BLE devices at startup

device/bluetooth/test/mock_bluetooth_central_manager_mac.mm

Index: device/bluetooth/test/mock_bluetooth_central_manager_mac.mm
diff --git a/device/bluetooth/test/mock_bluetooth_central_manager_mac.mm b/device/bluetooth/test/mock_bluetooth_central_manager_mac.mm
index fbb0dff41e75d315a5044a6e61dde508fe7382fd..16e216e4fc050aeaea7622f8bea583fd9ede18f4 100644
--- a/device/bluetooth/test/mock_bluetooth_central_manager_mac.mm
+++ b/device/bluetooth/test/mock_bluetooth_central_manager_mac.mm
@@ -14,6 +14,7 @@ @implementation MockCentralManager
 @synthesize delegate = _delegate;
 @synthesize state = _state;
 @synthesize bluetoothTestMac = _bluetoothTestMac;
+@synthesize connected_peripherals = _connected_peripherals;
 
 - (BOOL)isKindOfClass:(Class)aClass {
   if (aClass == [CBCentralManager class] ||
@@ -31,6 +32,10 @@ - (BOOL)isMemberOfClass:(Class)aClass {
   return [super isKindOfClass:aClass];
 }
 
+- (NSArray*)retrieveConnectedPeripheralsWithServices:(NSArray*)serviceUUIDs {
+  return _connected_peripherals;
+}
+
 - (void)scanForPeripheralsWithServices:(NSArray*)serviceUUIDs
                                options:(NSDictionary*)options {
   _scanForPeripheralsCallCount++;