Invoke GattDiscoveryCompleteForService by observing ServicesResolved property

device/bluetooth/bluez/bluetooth_device_bluez.h

Index: device/bluetooth/bluez/bluetooth_device_bluez.h
diff --git a/device/bluetooth/bluez/bluetooth_device_bluez.h b/device/bluetooth/bluez/bluetooth_device_bluez.h
index 293c2466b6dafe10bbf817fd9160660f3b179563..a7576a580e17d23196eee9f29dacee39d57b8d29 100644
--- a/device/bluetooth/bluez/bluetooth_device_bluez.h
+++ b/device/bluetooth/bluez/bluetooth_device_bluez.h
@@ -38,6 +38,7 @@ class BluetoothPairingBlueZ;
 // thread.
 class DEVICE_BLUETOOTH_EXPORT BluetoothDeviceBlueZ
     : public device::BluetoothDevice,
+      public bluez::BluetoothDeviceClient::Observer,
       public bluez::BluetoothGattServiceClient::Observer {
  public:
   // BluetoothDevice override
@@ -124,10 +125,19 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDeviceBlueZ
       scoped_refptr<device::BluetoothSocketThread> socket_thread);
   ~BluetoothDeviceBlueZ() override;
 
-  // bluez::BluetoothGattServiceClient::Observer overrides.
+  // bluez::BluetoothDeviceClient::Observer overrides
+  void DevicePropertyChanged(const dbus::ObjectPath& object_path,
+                             const std::string& property_name) override;
+
+  // bluez::BluetoothGattServiceClient::Observer overrides
   void GattServiceAdded(const dbus::ObjectPath& object_path) override;
   void GattServiceRemoved(const dbus::ObjectPath& object_path) override;
 
+  // Called by the constructor to initialize the map of GATT services associated
+  // with this device and to invoke NotifyGattDiscoveryComplete() with each
+  // cached service.
+  void InitializeGattServiceMap();
+
   // Called by dbus:: on completion of the D-Bus method call to get the
   // connection attributes of the current connection to the device.
   void OnGetConnInfo(const ConnectionInfoCallback& callback,
@@ -206,6 +216,13 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDeviceBlueZ
   scoped_refptr<base::SequencedTaskRunner> ui_task_runner_;
   scoped_refptr<device::BluetoothSocketThread> socket_thread_;
 
+  // This vector temporarily caches the newly added services for later
+  // notification of discovery complete. Once DevicePropertyChange is invoked
+  // with a toggle of ServicesResolved property, the
+  // NotifyGattDiscoveryComplete() will be called with each service once.
+  std::vector<device::BluetoothRemoteGattService*>
+      newly_discovered_gatt_services_;
+
   // During pairing this is set to an object that we don't own, but on which
   // we can make method calls to request, display or confirm PIN Codes and
   // Passkeys. Generally it is the object that owns this one.