Small cleanups

Summary:
As per title, in this diff:
1. LifecycleAware PoolScope no longer holds onto the lifecycle instance.
2. RecyclerBinder.Builder.poolScope method is annotated with ExperimentalLithoApi annotation.
3. ComponentTree only sets implicit tree prop if appropriate ComponentsConfiguration flags are enabled.

Reviewed By: fbcbl, luluwu2032

Differential Revision: D64689427

fbshipit-source-id: 12ad1d389582380555fbc90d70e0bed6c97e0e10

litho-core/src/main/java/com/facebook/litho/ComponentTree.java

@@ -375,11 +375,9 @@ protected ComponentTree(Builder builder) {
     if (ComponentsConfiguration.defaultInstance.enableLifecycleOwnerWrapper) {
       LifecycleOwner implicitLifecycleOwner = getImplicitLifecycleOwner(builder.treePropContainer);
       mImplicitTreePropContainer = createImplicitTreePropContainer(implicitLifecycleOwner);
-    }
-
-    @Nullable final PoolScope poolScope = builder.mPoolScope;
-    if (poolScope != null) {
-      mImplicitTreePropContainer.put(PoolScopeTreeProp, poolScope);
+      if (ComponentsConfiguration.customPoolScopesEnabled) {
+        mImplicitTreePropContainer.put(PoolScopeTreeProp, builder.mPoolScope);
+      }
     }
 
     if (useComponentTreePropContainerAsSourceOfTruth) {

litho-rendercore/src/main/java/com/facebook/rendercore/MountItemsPool.kt

@@ -581,7 +581,7 @@ sealed interface PoolScope {
    * A pool scope that automatically releases the pool when the given [lifecycle] transitions to
    * destroyed state
    */
-  class LifecycleAware(private val lifecycle: Lifecycle) : PoolScope {
+  class LifecycleAware(lifecycle: Lifecycle) : PoolScope {
     init {
       lifecycle.addObserver(
           object : DefaultLifecycleObserver {

litho-widget/src/main/java/com/facebook/litho/widget/RecyclerBinder.java

@@ -69,6 +69,7 @@
 import com.facebook.litho.Size;
 import com.facebook.litho.SizeSpec;
 import com.facebook.litho.ThreadUtils;
+import com.facebook.litho.annotations.ExperimentalLithoApi;
 import com.facebook.litho.choreographercompat.ChoreographerCompat;
 import com.facebook.litho.choreographercompat.ChoreographerCompatImpl;
 import com.facebook.litho.config.ComponentsConfiguration;
@@ -602,6 +603,7 @@ public Builder errorHandler(@Nullable Function1<Exception, Unit> handler) {
       return this;
     }
 
+    @ExperimentalLithoApi
     public Builder poolScope(PoolScope poolScope) {
       this.poolScope = poolScope;
       return this;