Fix leaks in BaseBindingFragment

[Goooler]

Activity → addFragment(AFragment()) → replaceFragment(BFragment(), isAddToBackStack = true) → bFragment.onDestroyView() → leaked

[Goooler]

Release binding's reference when next fragment was attached to parent with replaceFragment(isAddToBackStack = true)

[Goooler]

The previous fragment was called onDestroyView() but not onDestroy(), LeakCanary analyzes the view held by fragment should be released.

[Goooler]

┬───
│ GC Root: Thread object
│
├─ Bk instance
│    Leaking: NO (PathClassLoader↓ is not leaking)
│    Thread name: 'CleanupReference'
│    ↓ Thread.contextClassLoader
├─ dalvik.system.PathClassLoader instance
│    Leaking: NO (InternalLeakCanary↓ is not leaking and A ClassLoader is never
│    leaking)
│    ↓ ClassLoader.runtimeInternalObjects
├─ java.lang.Object[] array
│    Leaking: NO (InternalLeakCanary↓ is not leaking)
│    ↓ Object[896]
├─ leakcanary.internal.InternalLeakCanary class
│    Leaking: NO (WebActivity↓ is not leaking and a class is never leaking)
│    ↓ static InternalLeakCanary.resumedActivity
├─ io.goooler.demoapp.web.WebActivity instance
│    Leaking: NO (BlankFragment↓ is not leaking and Activity#mDestroyed is
│    false)
│    mApplication instance of io.goooler.demoapp.DemoApplication
│    mBase instance of androidx.appcompat.view.ContextThemeWrapper
│    ↓ ComponentActivity.mActivityResultRegistry
├─ androidx.activity.ComponentActivity$2 instance
│    Leaking: NO (BlankFragment↓ is not leaking)
│    Anonymous subclass of androidx.activity.result.ActivityResultRegistry
│    this$0 instance of io.goooler.demoapp.web.WebActivity with mDestroyed =
│    false
│    ↓ ActivityResultRegistry.mKeyToCallback
├─ java.util.HashMap instance
│    Leaking: NO (BlankFragment↓ is not leaking)
│    ↓
│    HashMap["FragmentManager:ad37cf17-b2a0-4eeb-979a-4915d3565c96:StartIntentSe
│    nderForResult"]
├─ androidx.activity.result.ActivityResultRegistry$CallbackAndContract instance
│    Leaking: NO (BlankFragment↓ is not leaking)
│    ↓ ActivityResultRegistry$CallbackAndContract.mCallback
├─ androidx.fragment.app.FragmentManager$8 instance
│    Leaking: NO (BlankFragment↓ is not leaking)
│    Anonymous class implementing androidx.activity.result.
│    ActivityResultCallback
│    ↓ FragmentManager$8.this$0
├─ androidx.fragment.app.FragmentManagerImpl instance
│    Leaking: NO (BlankFragment↓ is not leaking)
│    ↓ FragmentManager.mParent
├─ io.goooler.demoapp.web.BlankFragment instance
│    Leaking: NO (Fragment#mFragmentManager is not null)
│    ↓ BlankFragment.binding
│                    ~~~~~~~
├─ io.goooler.demoapp.web.databinding.BlankFragmentBindingImpl instance
│    Leaking: UNKNOWN
│    Retaining 13.3 kB in 135 objects
│    ↓ ViewDataBinding.mRoot
│                      ~~~~~
╰→ androidx.constraintlayout.widget.ConstraintLayout instance
     Leaking: YES (ObjectWatcher was watching this because io.goooler.demoapp.
     web.BlankFragment received Fragment#onDestroyView() callback (references
     to its views should be cleared to prevent leaks))
     Retaining 13.2 kB in 131 objects
     key = 1ffe3906-50c6-474a-98f0-e0aad80f61de
     watchDurationMillis = 10351
     retainedDurationMillis = 5351
     View not part of a window view hierarchy
     View.mAttachInfo is null (view detached)
     View.mWindowAttachCount = 1
     mContext instance of io.goooler.demoapp.web.WebActivity with mDestroyed =
     false

METADATA

Build.VERSION.SDK_INT: 30
Build.MANUFACTURER: OnePlus
LeakCanary version: 2.8.1
App process name: io.goooler.demoapp
Stats: LruCache[maxSize=3000,hits=43896,misses=112800,hitRate=28%]
RandomAccess[bytes=13775117,reads=112800,travel=56667537741,range=33309943,size=
39913741]
Analysis duration: 3553 ms

[Goooler]

https://github.com/square/leakcanary/blob/18f364bcbe14fc31547cb0c18e52414da999370f/leakcanary-object-watcher-android-androidx/src/main/java/leakcanary/internal/AndroidXFragmentDestroyWatcher.kt#L52-L60