Restore flow on device_tracker platform (#6374)

* Restore flow on device_tracker platform

* fix flow

* fix lint

homeassistant/components/device_tracker/__init__.py

@@ -132,18 +132,6 @@ def async_setup(hass: HomeAssistantType, config: ConfigType):
     devices = yield from async_load_config(yaml_path, hass, consider_home)
     tracker = DeviceTracker(hass, consider_home, track_new, devices)
 
-    # added_to_hass
-    add_tasks = [device.async_added_to_hass() for device in devices
-                 if device.track]
-    if add_tasks:
-        yield from asyncio.wait(add_tasks, loop=hass.loop)
-
-    # update tracked devices
-    update_tasks = [device.async_update_ha_state() for device in devices
-                    if device.track]
-    if update_tasks:
-        yield from asyncio.wait(update_tasks, loop=hass.loop)
-
     @asyncio.coroutine
     def async_setup_platform(p_type, p_config, disc_info=None):
         """Setup a device tracker platform."""
@@ -226,6 +214,8 @@ def async_setup(hass: HomeAssistantType, config: ConfigType):
     hass.services.async_register(
         DOMAIN, SERVICE_SEE, async_see_service, descriptions.get(SERVICE_SEE))
 
+    # restore
+    yield from tracker.async_setup_tracked_device()
     return True
 
 
@@ -356,6 +346,27 @@ class DeviceTracker(object):
                device.stale(now):
                 self.hass.async_add_job(device.async_update_ha_state(True))
 
+    @asyncio.coroutine
+    def async_setup_tracked_device(self):
+        """Setup all not exists tracked devices.
+
+        This method is a coroutine.
+        """
+        @asyncio.coroutine
+        def async_init_single_device(dev):
+            """Init a single device_tracker entity."""
+            yield from dev.async_added_to_hass()
+            yield from dev.async_update_ha_state()
+
+        tasks = []
+        for device in self.devices.values():
+            if device.track and not device.last_seen:
+                tasks.append(self.hass.async_add_job(
+                    async_init_single_device(device)))
+
+        if tasks:
+            yield from asyncio.wait(tasks, loop=self.hass.loop)
+
 
 class Device(Entity):
     """Represent a tracked device."""