Add unique_id to Nest Sensors (#16869)

* Add unique_id

* Add device_info

* Fix typo

* Update __init__.py

homeassistant/components/nest/__init__.py

@@ -309,6 +309,37 @@ class NestSensorDevice(Entity):
         """Do not need poll thanks using Nest streaming API."""
         return False
 
+    @property
+    def unique_id(self):
+        """Return unique id based on device serial and variable."""
+        return "{}-{}".format(self.device.serial, self.variable)
+
+    @property
+    def device_info(self):
+        """Return information about the device."""
+        if not hasattr(self.device, 'name_long'):
+            name = self.structure.name
+            model = "Structure"
+        else:
+            name = self.device.name_long
+            if self.device.is_thermostat:
+                model = 'Thermostat'
+            elif self.device.is_camera:
+                model = 'Camera'
+            elif self.device.is_smoke_co_alarm:
+                model = 'Nest Protect'
+            else:
+                model = None
+
+        return {
+            'identifiers': {
+                (DOMAIN, self.device.serial)
+            },
+            'name': name,
+            'manufacturer': 'Nest Labs',
+            'model': model,
+        }
+
     def update(self):
         """Do not use NestSensorDevice directly."""
         raise NotImplementedError