Remove non-bridgeless code paths from ReactDelegate / ReactActivityDelegate / ReactActivity / ReactFragment

Summary:
Third in a stack that collapses Android-side branches on `ReactNativeNewArchitectureFeatureFlags.enableBridgelessArchitecture()` under the standing assumption that on Android the flag is always `true`. The underlying generated `ReactNativeFeatureFlags.enableBridgelessArchitecture()` is untouched.

This is the cascade cleanup: with every lifecycle method in `ReactDelegate` always taking the `ReactHost` path, the fields, constructors, and helper methods that exist only to support the `ReactNativeHost`/`ReactInstanceManager` (bridge) path are now dead.

Removed from `ReactDelegate`:
- The deprecated 4-arg `(Activity, ReactNativeHost?, String?, Bundle?)` constructor
- The deprecated 5-arg `(Activity, ReactNativeHost?, String?, Bundle?, Boolean)` constructor
- `getReactInstanceManager()` (was reading through the removed `ReactNativeHost`)
- `createRootView()` (only the legacy `loadApp` branch called it)
- `isFabricEnabled` (only `createRootView` read it)
- `internalReactRootView` field and the corresponding `reactRootView` setter (the property is now a `val` returning `reactSurface?.view`)
- The private `reactNativeHost` field

Every public lifecycle method (`onHostResume`, `onUserLeaveHint`, `onHostPause`, `onHostDestroy`, `onBackPressed`, `onNewIntent`, `onActivityResult`, `onWindowFocusChanged`, `onConfigurationChanged`, `onKeyDown`, `onKeyLongPress`, `reload`, `loadApp`, `unloadApp`, `currentReactContext`) collapses to the `ReactHost`-only path.

Removed from `ReactActivityDelegate`:
- `getReactNativeHost()` and `getReactInstanceManager()` (both deprecated, fed the dead `ReactDelegate` machinery)
- `setReactRootView(ReactRootView)` (matched the removed `ReactDelegate.reactRootView` setter)
- The non-bridgeless branch in `onCreate` (the anonymous-subclass override of `createRootView` goes with it)
- The non-bridgeless branch in `onRequestPermissionsResult`

Removed from `ReactActivity`:
- `getReactNativeHost()` and `getReactInstanceManager()` (matched the delegate removals)

Removed from `ReactFragment`:
- The `reactNativeHost` property
- The non-bridgeless branch in `onCreate` (the `ARG_FABRIC_ENABLED` argument is now ignored; the constant + Builder API remain for backward compatibility)

`ReactAndroid.api` regenerated to reflect the 12 removed public/protected methods. `arc f` auto-removed the now-unused `ReactNativeNewArchitectureFeatureFlags` imports.

Subsequent diff in the stack will handle the wrapper method + lint detector.

Changelog:
[Android][Breaking] - Remove deprecated `ReactDelegate(Activity, ReactNativeHost, String, Bundle)` and `ReactDelegate(Activity, ReactNativeHost, String, Bundle, boolean)` constructors. Use the `ReactHost` constructor instead.
[Android][Breaking] - Remove `ReactDelegate.getReactInstanceManager()`, `ReactDelegate.createRootView()`, `ReactDelegate.isFabricEnabled`, and the `ReactDelegate.reactRootView` setter.
[Android][Breaking] - Remove `ReactActivityDelegate.getReactNativeHost()`, `ReactActivityDelegate.getReactInstanceManager()`, and `ReactActivityDelegate.setReactRootView(ReactRootView)`. Use `getReactHost()` and `setReactSurface(ReactSurface)` instead.
[Android][Breaking] - Remove `ReactActivity.getReactNativeHost()` and `ReactActivity.getReactInstanceManager()`. Use `getReactHost()` instead.
[Android][Breaking] - Remove `ReactFragment.reactNativeHost` property. Use `reactHost` instead.

Reviewed By: christophpurrer

Differential Revision: D106719840

Author: mdvacca

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

@@ -65,8 +65,6 @@ public abstract class com/facebook/react/ReactActivity : androidx/appcompat/app/
 	public fun getReactActivityDelegate ()Lcom/facebook/react/ReactActivityDelegate;
 	public fun getReactDelegate ()Lcom/facebook/react/ReactDelegate;
 	protected fun getReactHost ()Lcom/facebook/react/ReactHost;
-	protected final fun getReactInstanceManager ()Lcom/facebook/react/ReactInstanceManager;
-	protected final fun getReactNativeHost ()Lcom/facebook/react/ReactNativeHost;
 	public fun invokeDefaultOnBackPressed ()V
 	protected final fun loadApp (Ljava/lang/String;)V
 	public fun onActivityResult (IILandroid/content/Intent;)V
@@ -99,8 +97,6 @@ public class com/facebook/react/ReactActivityDelegate {
 	protected fun getReactActivity ()Lcom/facebook/react/ReactActivity;
 	protected fun getReactDelegate ()Lcom/facebook/react/ReactDelegate;
 	public fun getReactHost ()Lcom/facebook/react/ReactHost;
-	public fun getReactInstanceManager ()Lcom/facebook/react/ReactInstanceManager;
-	protected fun getReactNativeHost ()Lcom/facebook/react/ReactNativeHost;
 	protected fun isFabricEnabled ()Z
 	protected fun isWideColorGamutEnabled ()Z
 	protected fun loadApp (Ljava/lang/String;)V
@@ -119,7 +115,6 @@ public class com/facebook/react/ReactActivityDelegate {
 	public fun onUserLeaveHint ()V
 	public fun onWindowFocusChanged (Z)V
 	public fun requestPermissions ([Ljava/lang/String;ILcom/facebook/react/modules/core/PermissionListener;)V
-	public fun setReactRootView (Lcom/facebook/react/ReactRootView;)V
 	public fun setReactSurface (Lcom/facebook/react/interfaces/fabric/ReactSurface;)V
 }
 
@@ -130,14 +125,9 @@ public abstract interface class com/facebook/react/ReactApplication {
 
 public class com/facebook/react/ReactDelegate {
 	public fun <init> (Landroid/app/Activity;Lcom/facebook/react/ReactHost;Ljava/lang/String;Landroid/os/Bundle;)V
-	public fun <init> (Landroid/app/Activity;Lcom/facebook/react/ReactNativeHost;Ljava/lang/String;Landroid/os/Bundle;)V
-	public fun <init> (Landroid/app/Activity;Lcom/facebook/react/ReactNativeHost;Ljava/lang/String;Landroid/os/Bundle;Z)V
-	protected fun createRootView ()Lcom/facebook/react/ReactRootView;
 	public final fun getCurrentReactContext ()Lcom/facebook/react/bridge/ReactContext;
 	public final fun getReactHost ()Lcom/facebook/react/ReactHost;
-	public final fun getReactInstanceManager ()Lcom/facebook/react/ReactInstanceManager;
 	public final fun getReactRootView ()Lcom/facebook/react/ReactRootView;
-	protected final fun isFabricEnabled ()Z
 	public final fun loadApp ()V
 	public final fun loadApp (Ljava/lang/String;)V
 	public final fun onActivityResult (IILandroid/content/Intent;Z)V
@@ -152,7 +142,6 @@ public class com/facebook/react/ReactDelegate {
 	public final fun onUserLeaveHint ()V
 	public final fun onWindowFocusChanged (Z)V
 	public final fun reload ()V
-	public final fun setReactRootView (Lcom/facebook/react/ReactRootView;)V
 	public final fun setReactSurface (Lcom/facebook/react/interfaces/fabric/ReactSurface;)V
 	public final fun shouldShowDevMenuOrReload (ILandroid/view/KeyEvent;)Z
 	public final fun unloadApp ()V
@@ -170,7 +159,6 @@ public class com/facebook/react/ReactFragment : androidx/fragment/app/Fragment,
 	public fun checkSelfPermission (Ljava/lang/String;)I
 	protected final fun getReactDelegate ()Lcom/facebook/react/ReactDelegate;
 	protected fun getReactHost ()Lcom/facebook/react/ReactHost;
-	protected fun getReactNativeHost ()Lcom/facebook/react/ReactNativeHost;
 	public fun onActivityResult (IILandroid/content/Intent;)V
 	public fun onBackPressed ()Z
 	public fun onCreate (Landroid/os/Bundle;)V

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

@@ -167,18 +167,10 @@ public void onConfigurationChanged(@NotNull Configuration newConfig) {
     mDelegate.onConfigurationChanged(newConfig);
   }
 
-  protected final ReactNativeHost getReactNativeHost() {
-    return mDelegate.getReactNativeHost();
-  }
-
   protected ReactHost getReactHost() {
     return mDelegate.getReactHost();
   }
 
-  protected final ReactInstanceManager getReactInstanceManager() {
-    return mDelegate.getReactInstanceManager();
-  }
-
   protected final void loadApp(String appKey) {
     mDelegate.loadApp(appKey);
   }

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

@@ -23,7 +23,6 @@
 import com.facebook.react.bridge.ReactContext;
 import com.facebook.react.common.LifecycleState;
 import com.facebook.react.interfaces.fabric.ReactSurface;
-import com.facebook.react.internal.featureflags.ReactNativeNewArchitectureFeatureFlags;
 import com.facebook.react.modules.core.PermissionListener;
 import com.facebook.react.views.view.WindowUtilKt;
 import com.facebook.systrace.Systrace;
@@ -83,21 +82,6 @@ public ReactActivityDelegate(
     return null;
   }
 
-  /**
-   * Get the {@link ReactNativeHost} used by this app with Bridge enabled. By default, assumes
-   * {@link Activity#getApplication()} is an instance of {@link ReactApplication} and calls {@link
-   * ReactApplication#getReactNativeHost()}. Override this method if your application class does not
-   * implement {@code ReactApplication} or you simply have a different mechanism for storing a
-   * {@code ReactNativeHost}, e.g. as a static field somewhere.
-   *
-   * @deprecated "Do not access {@link ReactNativeHost} directly. This class is going away in the
-   *     New Architecture. You should access {@link ReactHost} instead."
-   */
-  @Deprecated
-  protected ReactNativeHost getReactNativeHost() {
-    return ((ReactApplication) getPlainActivity().getApplication()).getReactNativeHost();
-  }
-
   /**
    * Get the {@link ReactHost} used by this app with Bridgeless enabled. By default, assumes {@link
    * Activity#getApplication()} is an instance of {@link ReactApplication} and calls {@link
@@ -113,16 +97,6 @@ protected ReactNativeHost getReactNativeHost() {
     return mReactDelegate;
   }
 
-  /**
-   * @deprecated @deprecated "Do not access {@link ReactInstanceManager} directly. This class is
-   *     going away in the New Architecture. You should access {@link ReactHost} instead."
-   * @noinspection deprecation
-   */
-  @Deprecated
-  public ReactInstanceManager getReactInstanceManager() {
-    return Objects.requireNonNull(mReactDelegate).getReactInstanceManager();
-  }
-
   @Nullable
   public String getMainComponentName() {
     return mMainComponentName;
@@ -144,29 +118,9 @@ public void onCreate(@Nullable Bundle savedInstanceState) {
               }
             }
           }
-          if (ReactNativeNewArchitectureFeatureFlags.enableBridgelessArchitecture()) {
-            mReactDelegate =
-                new ReactDelegate(
-                    getPlainActivity(), getReactHost(), mainComponentName, launchOptions);
-          } else {
-            mReactDelegate =
-                new ReactDelegate(
-                    getPlainActivity(),
-                    getReactNativeHost(),
-                    mainComponentName,
-                    launchOptions,
-                    isFabricEnabled()) {
-                  @Override
-                  @Nullable
-                  protected ReactRootView createRootView() {
-                    ReactRootView rootView = ReactActivityDelegate.this.createRootView();
-                    if (rootView == null) {
-                      rootView = super.createRootView();
-                    }
-                    return rootView;
-                  }
-                };
-          }
+          mReactDelegate =
+              new ReactDelegate(
+                  getPlainActivity(), getReactHost(), mainComponentName, launchOptions);
           if (mainComponentName != null) {
             loadApp(mainComponentName);
           }
@@ -182,10 +136,6 @@ public void setReactSurface(ReactSurface reactSurface) {
     Objects.requireNonNull(mReactDelegate).setReactSurface(reactSurface);
   }
 
-  public void setReactRootView(ReactRootView reactRootView) {
-    Objects.requireNonNull(mReactDelegate).setReactRootView(reactRootView);
-  }
-
   public void onUserLeaveHint() {
     Objects.requireNonNull(mReactDelegate).onUserLeaveHint();
   }
@@ -256,18 +206,9 @@ public void onRequestPermissionsResult(
           }
         };
 
-    LifecycleState lifecycle;
-    if (isFabricEnabled()) {
-      ReactHost reactHost = getReactHost();
-      lifecycle = reactHost != null ? reactHost.getLifecycleState() : LifecycleState.BEFORE_CREATE;
-    } else {
-      ReactNativeHost reactNativeHost = getReactNativeHost();
-      if (!reactNativeHost.hasInstance()) {
-        lifecycle = LifecycleState.BEFORE_CREATE;
-      } else {
-        lifecycle = reactNativeHost.getReactInstanceManager().getLifecycleState();
-      }
-    }
+    ReactHost reactHost = getReactHost();
+    LifecycleState lifecycle =
+        reactHost != null ? reactHost.getLifecycleState() : LifecycleState.BEFORE_CREATE;
 
     // If the permission request didn't show a dialog to the user, we can call the callback
     // immediately.