RN changes to enable fragment-based navigation [1/3] (#43789)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43789

This diff introduces some changes to React Native needed to enable fragment-based navigation (see next diff for usage).

Fragment-based navigation will enable us to, instead of re-creating the entire main activity on navigation, create a fragment instead - allowing us to bypass a lot of unnecessary onCreate() logic in our main activity to improve user experience and performance.

Changelog:
[Internal] [Changed] - Add option to skip calling delegate on ReactFragment lifecycle events

Reviewed By: keoskate

Differential Revision: D55646221

fbshipit-source-id: 45b148cb9ecdb1484f1ac714ac2b93ce09c52237

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -92,6 +92,7 @@ public abstract class com/facebook/react/ReactActivity : androidx/appcompat/app/
 	protected fun <init> ()V
 	protected fun createReactActivityDelegate ()Lcom/facebook/react/ReactActivityDelegate;
 	protected fun getMainComponentName ()Ljava/lang/String;
+	public fun getReactActivityDelegate ()Lcom/facebook/react/ReactActivityDelegate;
 	public fun getReactDelegate ()V
 	protected final fun getReactInstanceManager ()Lcom/facebook/react/ReactInstanceManager;
 	protected final fun getReactNativeHost ()Lcom/facebook/react/ReactNativeHost;
@@ -178,6 +179,7 @@ public class com/facebook/react/ReactFragment : androidx/fragment/app/Fragment,
 	protected static final field ARG_FABRIC_ENABLED Ljava/lang/String;
 	protected static final field ARG_LAUNCH_OPTIONS Ljava/lang/String;
 	protected field mReactDelegate Lcom/facebook/react/ReactDelegate;
+	protected field shouldCallDelegateLifecycleEvents Z
 	public fun <init> ()V
 	public fun checkPermission (Ljava/lang/String;II)I
 	public fun checkSelfPermission (Ljava/lang/String;)I

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactActivity.java

@@ -69,6 +69,10 @@ public abstract class ReactActivity extends AppCompatActivity
     mDelegate.getReactDelegate();
   }
 
+  public ReactActivityDelegate getReactActivityDelegate() {
+    return mDelegate;
+  }
+
   @Override
   public void onActivityResult(int requestCode, int resultCode, Intent data) {
     super.onActivityResult(requestCode, resultCode, data);

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactFragment.java

@@ -32,6 +32,8 @@ public class ReactFragment extends Fragment implements PermissionAwareActivity {
 
   protected ReactDelegate mReactDelegate;
 
+  protected boolean shouldCallDelegateLifecycleEvents = true;
+
   @Nullable private PermissionListener mPermissionListener;
 
   public ReactFragment() {
@@ -99,19 +101,25 @@ public class ReactFragment extends Fragment implements PermissionAwareActivity {
   @Override
   public void onResume() {
     super.onResume();
-    mReactDelegate.onHostResume();
+    if (shouldCallDelegateLifecycleEvents) {
+      mReactDelegate.onHostResume();
+    }
   }
 
   @Override
   public void onPause() {
     super.onPause();
-    mReactDelegate.onHostPause();
+    if (shouldCallDelegateLifecycleEvents) {
+      mReactDelegate.onHostPause();
+    }
   }
 
   @Override
   public void onDestroy() {
     super.onDestroy();
-    mReactDelegate.onHostDestroy();
+    if (shouldCallDelegateLifecycleEvents) {
+      mReactDelegate.onHostDestroy();
+    }
   }
 
   // endregion