WidgetsBindingObserver constructor Null safety

1. Flutter
2. widgets
3. WidgetsBindingObserver
4. WidgetsBindingObserver constructor

WidgetsBindingObserver class

1. Constructors
2. WidgetsBindingObserver
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. didChangeAccessibilityFeatures
8. didChangeAppLifecycleState
9. didChangeLocales
10. didChangeMetrics
11. didChangePlatformBrightness
12. didChangeTextScaleFactor
13. didHaveMemoryPressure
14. didPopRoute
15. didPushRoute
16. didPushRouteInformation
17. noSuchMethod
18. toString
19. Operators
20. operator ==